Chickpea Pesto Burgers with Roasted-Red Pepper Sauce

1. To prepare roasted onion: Preheat oven to 375°F and place a baking sheet in the oven while it preheats. Toss onion with 1 tablespoon oil, 1 tablespoon vinegar, ¼ teaspoon salt and pepper in a small bowl. Transfer the mixture to one side of an 18-inch piece of foil. Fold the foil in half and crimp the edges to seal the onion in a packet. Place the packet on the baking sheet and bake until the onion is tender, 20 to 30 minutes.

2. Meanwhile, prepare burgers: Squeeze extra liquid out of spinach and place the spinach in a medium bowl. Add chickpeas and mash with a fork. Add egg, walnuts, breadcrumbs, pesto and salt and mix well. Form the mixture into six ¾-inch-thick patties.

3. Heat oil in a large nonstick skillet over medium-high heat. Add the patties and cook until golden brown on the bottom, 5 to 6 minutes. Flip the patties, reduce heat to medium-low, cover and cook until the other side is golden brown and an instant-read thermometer inserted in the center registers 160°F, about 5 minutes more.

4. Meanwhile, prepare sauce: Combine 1 roasted pepper, garlic, mayonnaise (and/or yogurt) and vinegar in a small food processor. Process until smooth. Slice the remaining roasted peppers into strips.

5. Place the burgers on buns and top with the sauce, roasted onion and pepper strips.

To make ahead

Refrigerate roasted onions (Step 1), burger patties (Step 2) and sauce (Step 4) separately for up to 1 day.

Tip

For the best flavor, toast nuts before using in a recipe. To toast chopped nuts, place in a small dry skillet and cook over medium-low heat, stirring constantly, until fragrant, 2 to 4 minutes.