Black Bean and Mushroom Sliders

Hollow out top halves of buns, leaving a 1/2-inch-thick shell. Place the torn bread in a food processor; pulse until coarse crumbs form. Place crumbs in a large nonstick skillet over medium heat; cook 3 minutes or until toasted, stirring frequently. Cool completely.

Place half of mushrooms on a microwave-safe plate; microwave at HIGH for 5 minutes, stirring mushrooms once. Repeat procedure with remaining mushroom slices.

Coarsely chop onions, and place in food processor. Add garlic; process until finely chopped. Add mushrooms and black beans; pulse 4 to 5 times. Transfer mixture to a large bowl; stir in reserved breadcrumbs, lemon juice, cumin, 1/4 teaspoon salt, pepper, and egg white. Divide bean mixture into 8 equal portions (about 1/3 cup each), shaping each into a 3/4-inch-thick patty.

Heat a skillet over medium heat. Add 1 teaspoon oil; swirl to coat. Add 4 patties; cook 3 minutes on each side or until browned and thoroughly heated. Repeat with remaining oil and remaining patties. Place sliders on buns; spread evenly with mayonnaise.

Combine avocado, orange sections, and remaining 1/8 teaspoon salt. Serve with sliders.