Preheat the oven to 425°F (218°C).
Ensure the canned chickpeas are drained and rinsed. Place 4 cups cauliflower florets and the chickpeas on a baking sheet. Drizzle with 3 tablespoons olive oil and toss to coat.
Evenly sprinkle 1 teaspoon turmeric, ½ teaspoon ground ginger, and ½ teaspoon garlic powder over the cauliflower and chickpeas. Season with kosher salt and pepper to taste and toss again to distribute the spices. Spread in a single layer on the baking sheet.
Roast until the cauliflower is golden and crispy at the edges, about 25 to 30 minutes, tossing once or twice during the cook time for even browning.
While the cauliflower and chickpeas roast, cook the couscous or your chosen grain according to package instructions so it is ready for serving.
Make the hummus dressing: in a bowl whisk together ¼ cup plain hummus, the juice of ½ lemon, 1 teaspoon honey, 1 teaspoon grated fresh ginger, and a pinch of kosher salt and pepper until smooth.
Whisk in 2 to 3 tablespoons cold water, adding it gradually, until the dressing reaches a smooth, pourable consistency.
To assemble, divide the cooked couscous among bowls, top with the roasted cauliflower and chickpeas, drizzle with the hummus dressing, and finish with fresh cilantro. Serve immediately.