This Roasted Tomato Basil Soup is the kind of recipe I turn to when I want something comforting, bright, and reliably simple. It leans on caramelized oven-roasting to concentrate tomato flavor, and fresh basil adds that clean green note that makes tomato soup feel like summer in a bowl. It’s forgiving, but a few small techniques make a big difference.

I love that the soup comes together mostly in the oven and finishes on the stovetop, leaving you free to make a crisp grilled cheese or set the table. The method highlights three things: good tomatoes, direct heat for caramelization, and a short simmer to let flavors meld. Few steps, clear outcomes.

You’ll find practical tips below for timing, tool choices, and how to adapt this for dietary needs. Read through once, then roast, blend, and serve. It’s straightforward and consistently satisfying.

Shopping List

2 1/4 lbs Roma tomatoes, halved lengthwise — the backbone of the soup; halving exposes flesh for even roasting and caramelization.
1 1/4 lbs grape tomatoes or cherry tomatoes — add juice and concentrated sweetness; use whichever you prefer.
4 1/2 Tbsp olive oil, divided — used for roasting both tomatoes and aromatics; keep some back for the onions and garlic.
Salt and black pepper — essential for seasoning during roasting and at the finish; adjust to taste.
8 cloves garlic, peeled and left whole — roasted whole for mellow, sweet garlic flavor without bitterness.
2 small yellow onions, sliced just under 1/2-inch thick — caramelize to add depth and a savory backbone to the soup.
1 1/2 cups (26 g) lightly packed fresh basil, divided — most goes into the pot for flavor; reserve some for garnish to keep that bright color and aroma.
5 cups low-sodium vegetable broth — builds the soup base; low-sodium lets you control final seasoning.
Prepared grilled cheese or grilled cheese croutons (optional), see notes — for serving; optional but highly recommended for a classic combo.

Roasted Tomato Basil Soup: Step-by-Step Guide

Preheat oven to 425°F.
On a rimmed baking sheet, arrange the 2 1/4 lbs Roma tomatoes cut side up and the 1 1/4 lbs grape or cherry tomatoes in a single layer. Toss the tomatoes with 3 Tbsp olive oil and season with salt and black pepper.
On a separate rimmed half sheet, arrange the 2 small yellow onions (sliced just under 1/2-inch thick) in a single layer and spread the 8 peeled whole garlic cloves among them. Drizzle or brush the onions and garlic with the remaining 1 1/2 Tbsp olive oil and season with salt and black pepper.
Place both sheets in the oven side by side. Roast the garlic for 15 minutes, or until just golden; remove the garlic from the oven and set aside.
Continue roasting the onions and tomatoes: roast the onions 30–35 minutes, until the edges are golden brown; roast the tomatoes 40–45 minutes, until they are slightly browned. (If your oven cooks unevenly, rotate the pans front-to-back halfway through roasting.)
Transfer the roasted tomatoes, roasted onions, roasted garlic, and any pan juices into a large pot. Add 5 cups low-sodium vegetable broth and about 3/4 of the 1 1/2 cups (26 g) lightly packed fresh basil; reserve the remaining basil for garnish. Season with salt and black pepper to taste.
Bring the pot to a boil over medium-high heat. Cover, reduce heat to low, and simmer for 20 minutes.
Remove the pot from the heat and let cool a few minutes to reduce splattering. Blend the soup until smooth using an immersion blender, or blend in batches in a regular blender (fill the blender no more than halfway, remove the center insert from the lid, cover the lid with a kitchen towel, and hold it while blending to allow steam to vent).
Return soup to the pot if needed and reheat gently. Chop the reserved basil and sprinkle it on top of each serving. Serve warm with prepared grilled cheese or grilled cheese croutons if desired.

Why I Love This Recipe

This soup sings because roasting does the heavy lifting. Direct oven heat concentrates tomato sugars and creates caramelized bits that give a richer, deeper tomato flavor than stovetop simmering alone. The roasted onions and garlic round out the acidity and bring savory balance without added cream.

It’s flexible. You can roast everything ahead, refrigerate, and finish the soup when you’re ready—perfect for dinner parties or weekday dinners. The texture becomes silky and elegant after blending, yet it’s still hearty and homey.

Substitutions by Category

Tomatoes — If fresh Roma or grape tomatoes aren’t available, use similarly meaty tomatoes or a mix of vine-ripened tomatoes for sweetness. Canned whole tomatoes can be used in a pinch, but roast them first for better depth.
Fat — Olive oil is preferred for flavor, but neutral oils (avocado, light olive) will work if needed.
Broth — Low-sodium vegetable broth is specified so you can control salt; use chicken broth for a non-vegetarian option if desired.
Herbs — Fresh basil is key for the bright finish. If fresh basil is unavailable, a small amount of chopped fresh parsley helps but will change the flavor profile.
Optional add-ins — If you want creaminess, a splash of cream or coconut milk at the end will alter the texture but is not necessary for flavor.

Hardware & Gadgets

Rimmed baking sheets — two sheets let you roast tomatoes and aromatics separately so timing stays precise.
Sharp chef’s knife — for halving tomatoes and slicing onions evenly.
Large heavy-bottomed pot — large enough to hold all roasted veg plus 5 cups broth.
Immersion blender — fastest and safest for blending hot soup directly in the pot. If you use a countertop blender, blend in small batches and vent the lid as instructed.
Oven mitts and kitchen towel — for handling hot pans and covering blender lids during venting.

Easy-to-Miss Gotchas

Crowded pans — overcrowding tomatoes or onions prevents proper browning. Use two pans as directed and space items in a single layer.
Uneven roasting — ovens vary. Rotate pans front-to-back halfway through to get even caramelization.
Blending hot liquid — always vent the blender and cover with a towel when blending hot soup. Hot steam can force the lid off and cause splatters.
Salt timing — start with modest salt during roasting; adjust after simmering and blending to account for concentration and broth salt level.
Basil timing — adding most basil to cook with the soup mellows it; reserve some fresh leaves for garnish to preserve aroma and color.

Health-Conscious Tweaks

Lower sodium — use no-salt-added broth and taste before salting at the end. Roasting intensifies flavors, so you’ll often need less salt than expected.
Lower fat — the total olive oil is modest; to reduce fat further, cut the oil for roasting by a tablespoon or two and rely on nonstick pans and even roasting heat. The soup will still be flavorful.
Dairy-free — the base recipe is dairy-free. If you want creaminess without dairy, stir in a small amount of full-fat coconut milk at the end for richness.
Boost fiber — keep more of the tomato skins if you don’t mind a slightly coarser texture; they add fiber and nutrients. Use a high-speed blender if you want it very smooth while retaining fiber.

Notes from the Test Kitchen

Timing matters: the garlic is removed after 15 minutes to avoid burning; it’ll be soft and sweet. The onions and tomatoes have different finish times, which is why they go on separate pans. We tested rotating pans halfway at 20 minutes and found much more even browning in standard home ovens.

Using low-sodium broth gives a predictable baseline. In testing, soups made with higher-sodium broths often needed no additional salt, while unsalted broths required a careful finish. We usually reserve a tablespoon of oil to add at the end for sheen if the soup feels dull.

If your tomatoes are exceptionally sweet or acidic, adjust basil and salt accordingly. Too sweet? A small splash of vinegar balances it. Too acidic? A pinch of sugar or a carrot roasted with the onions tames the sharp edge—but note these are optional adjustments, not required steps.

Shelf Life & Storage

Refrigerator — Store soup in an airtight container for up to 4 days. Reheat gently on the stovetop; avoid boiling to preserve fresh basil notes.
Freezer — Cool completely, then freeze in airtight containers or freezer bags for up to 3 months. Thaw overnight in the fridge and reheat slowly on low.
Make-ahead — You can roast tomatoes, onions, and garlic a day ahead. Store roasted vegetables refrigerated on the pan or in a shallow container and finish the soup within 24 hours for best flavor.

Helpful Q&A

Q: Can I skip roasting? A: You can simmer raw tomatoes, but roasting concentrates flavor and adds caramelized notes that elevate the soup.
Q: Can I use canned tomatoes? A: Yes. For best results, drain them slightly, spread on a pan, and roast briefly to reduce excess liquid and deepen flavor.
Q: How do I get a very smooth texture? A: Use an immersion blender for long blending, or a high-speed countertop blender and blend until silky. Passing through a fine-mesh sieve removes any remaining seeds or fibers.
Q: Is basil essential? A: Basil gives the signature finish. If you must substitute, parsley or a small amount of fresh oregano will change the profile but still be pleasant.
Q: Can I make this spicy? A: Add red pepper flakes during the simmer or a small pinch of cayenne when blending to introduce heat.

Next Steps

Serve this soup with a crisp grilled cheese or croutons made from a buttered grilled cheese cut into cubes. Garnish with the reserved chopped basil and a drizzle of olive oil for a glossy finish. For a dinner party, roast the tomatoes and aromatics earlier in the day and finish the soup just before guests arrive. Pair with a simple green salad and a crusty baguette.

Want variation ideas? Try stirring in a spoonful of pesto at the end for an herby lift, or top each bowl with a sprinkle of toasted seeds for crunch. Keep experimenting with tomato varieties and roasting time until you find your perfect balance of sweet, tangy, and savory.

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Roasted Tomato Basil Soup

A comforting roasted tomato and basil soup made by oven-roasting tomatoes, onions, and garlic, then blending with vegetable broth and fresh basil. Serve warm with grilled cheese or grilled cheese croutons if desired.

Servings: 6 servings

Ingredients

2 1/4 lbsRoma tomatoes halved lengthwise
1 1/4 lbsgrape tomatoesor cherry tomatoes
4 1/2 Tbspolive oil divided
Saltand black pepper
8 clovesgarlic peeled and left whole
2 small yellow onions sliced just under 1/2-inch thick
1 1/2 cups 26 g lightly packedfresh basil, divided
5 cupslow-sodium vegetable broth
Prepared grilled cheeseor grilled cheese croutons optional, see notes

Instructions

Preheat oven to 425°F.
On a rimmed baking sheet, arrange the 2 1/4 lbs Roma tomatoes cut side up and the 1 1/4 lbs grape or cherry tomatoes in a single layer. Toss the tomatoes with 3 Tbsp olive oil and season with salt and black pepper.
On a separate rimmed half sheet, arrange the 2 small yellow onions (sliced just under 1/2-inch thick) in a single layer and spread the 8 peeled whole garlic cloves among them. Drizzle or brush the onions and garlic with the remaining 1 1/2 Tbsp olive oil and season with salt and black pepper.
Place both sheets in the oven side by side. Roast the garlic for 15 minutes, or until just golden; remove the garlic from the oven and set aside.
Continue roasting the onions and tomatoes: roast the onions 30–35 minutes, until the edges are golden brown; roast the tomatoes 40–45 minutes, until they are slightly browned. (If your oven cooks unevenly, rotate the pans front-to-back halfway through roasting.)
Transfer the roasted tomatoes, roasted onions, roasted garlic, and any pan juices into a large pot. Add 5 cups low-sodium vegetable broth and about 3/4 of the 1 1/2 cups (26 g) lightly packed fresh basil; reserve the remaining basil for garnish. Season with salt and black pepper to taste.
Bring the pot to a boil over medium-high heat. Cover, reduce heat to low, and simmer for 20 minutes.
Remove the pot from the heat and let cool a few minutes to reduce splattering. Blend the soup until smooth using an immersion blender, or blend in batches in a regular blender (fill the blender no more than halfway, remove the center insert from the lid, cover the lid with a kitchen towel, and hold it while blending to allow steam to vent).
Return soup to the pot if needed and reheat gently. Chop the reserved basil and sprinkle it on top of each serving. Serve warm with prepared grilled cheese or grilled cheese croutons if desired.

Equipment

rimmed baking sheet
rimmed half sheet
Large Pot
immersion blender or blender
Kitchen Towel

Notes

Use6 slices of hearty sourdough, wheat or white bread. Brush outsides of all slices with1/2 Tbsp of butteron each.Sprinkle 1/2 cup (2 oz) shredded mozzarella or cheddarover non-buttered sides of three slices. Top with remaining 3 slices of bread with buttered side up. Cook in a skillet over medium heat, reducing to medium-low as needed, until bottom is golden brown. Flip and cook opposite side until golden. Cut in half if serving as a sandwich or if serving as croutons in the soup cool just slightly then cut into squares.
Optionally you can pull peels from tomatoes if preferred. You can also leave basil on the sprigs then remove sprigs before blending if desired.
For a creamy tomato soup you can add 1/2 cup to 1 cup heavy cream to the soup. For a cheesy flavor you can serve with finely shredded parmesan cheese.
Recipe makes about 9 cups soup.
Grilled cheese not included in nutrition estimate.

Prep Time10

Cook Time1 5

Total Time1 15

Course: Soup