Black Bean & Veggie Smash Burgers

Place rinsed black beans in a medium bowl; mash with a fork until mostly smooth with some pieces remaining. Add ⅔ cup mushrooms, ½ cup onion, ½ cup panko, the beaten egg, 1 tablespoon chipotle, the minced garlic and ½ teaspoon salt; stir until well combined. Divide the mixture into 4 (about 4-ounce) portions and shape into firm balls. Cover and refrigerate for at least 30 minutes or up to 12 hours.

Combine ¼ cup yogurt, 2 teaspoons ketchup and ½ teaspoon mustard in a small bowl.

Heat 1 tablespoon oil in a large nonstick skillet over medium-high heat. Add 2 bean balls to the skillet. Coat the bottom of a sturdy spatula with cooking spray and firmly press each ball into a 4-inch patty. Cook, undisturbed, until well browned and crisp around the edges, 2 to 3 minutes. Flip the patties and top each with 1 cheese slice. Cover and cook until the cheese is melted and the patties are heated through, about 2 minutes. Transfer to a plate. Repeat the process with the remaining 1 tablespoon oil, 2 bean balls and 2 cheese slices.

Spread about 1½ teaspoons sauce on each toasted bun half. Layer the bottom halves with a bean patty, 1 lettuce leaf and 1 tomato slice. Top with the top bun half.