Instructions

• Make the kale-mint pesto: in a food processor or blender, combine the chopped kale (4 cups tightly packed), mint leaves (1 cup), walnuts (1/2 cup), garlic (3 large cloves), and salt (1/4 teaspoon). Pulse until the ingredients are coarsely chopped.
• With the machine running on medium speed, slowly pour in the walnut oil (1/4 cup) and process until the mixture becomes a coarse pesto. Scrape down the sides as needed. Transfer the pesto to a bowl or container and set aside.
• Divide the ground lamb (1 pound) into three even portions and shape each into a burger patty roughly the diameter of your buns; press gently to an even thickness.
• Heat a large cast-iron skillet over medium heat until hot. Add the grapeseed or olive oil (1 tablespoon) and the unsalted butter (1 tablespoon) and let them melt and coat the pan.
• Place the three patties in the hot skillet, leaving space between them. Cook undisturbed for 5 minutes. Flip the patties and cook an additional 3 minutes.
• Place one slice of jack cheese on each patty and cover the skillet until the cheese melts and the meat reaches your desired doneness.
• While the patties are cooking, set the oven to broil and place the hamburger buns (3), cut-side up, on a baking sheet. Broil until the cut sides are golden brown and crispy—watch closely and remove as soon as they reach the desired color.
• Assemble the burgers: spread the kale-mint pesto on the cut sides of the toasted buns, place a cheesy lamb patty on each bottom bun, top each patty with a handful of spinach or spring green mix, and close with the top bun.
• Serve immediately.