Spicy Lentil-Walnut Burgers

Ingredients

• 3/4 cup toasted walnuts
• 1/3 cup plain dried breadcrumbs
• 3 cloves garlic, coarsely chopped
• 1 tablespoon minced jalapeno pepper
• 2 teaspoons ground cumin
• 2 teaspoons ground coriander
• 1/4 to 1/2 teaspoon crushed red pepper flakes
• coarse salt and freshly ground pepper
• 3/4 cup lentils, cooked, drained, and cooled
• 1/4 cup grated onion
• 4 tablespoons olive oil
• 1 large egg
• 4 large pitas
• yogurt-cilantro sauce, for serving
• sliced avocado, for serving
• cherry tomatoes, halved, for serving