Step 1

Place mushroom, black beans, almond butter, 1 tablespoon mayonnaise, pepper, paprika, 1/2 teaspoon garlic powder and salt in a food processor. Pulse, stopping once or twice to scrape down the sides, until a coarse mixture forms that holds together when pressed. Transfer to a bowl and add quinoa and oats; stir well to combine. Refrigerate for 1 hour.

Step 2

Meanwhile, whisk ketchup, mustard and the remaining 2 tablespoons mayonnaise and 1/4 teaspoon garlic powder in a small bowl until smooth.

Step 3

Shape the mushroom mixture into 4 patties.

Step 4

Heat oil in a large grill pan or nonstick skillet over medium-high heat. Add the patties and cook until golden and beginning to crisp, 4 to 5 minutes. Carefully flip and cook until golden brown, 2 to 4 minutes more.

Step 5

Serve the burgers on buns with the special sauce, lettuce, tomato and onion.