Mash the lentils: Pulse cooked lentils in a food processor until slightly mashed but still textured. Transfer to a bowl.
Chop the mushrooms: Pulse mushrooms in the food processor until finely chopped.
Sauté the aromatics: Heat olive oil in a skillet over medium heat. Cook onion and garlic for 2-3 minutes until soft and fragrant.
Cook the mushrooms: Add chopped mushrooms and cook for 5-7 minutes until all moisture evaporates. Let cool slightly.
Mix the ingredients: Combine lentils, mushrooms, onions, breadcrumbs, cumin, paprika, salt, pepper, and egg in the bowl. Mix until well combined.
Shape and chill: Form into ½-inch-thick patties and refrigerate for 30 minutes.
Cook the patties: Heat olive oil in a skillet over medium heat. Cook patties for 4-5 minutes per side until golden brown and crispy.
Assemble and serve: Place on toasted buns with your favorite toppings like lettuce, tomato, avocado, or hummus.