Mash cooked beans or lentils
Mix with breadcrumbs or oats
Add chopped onion and garlic
Add grated carrot or mushrooms
Season with salt, pepper, and spices
Stir in an egg or flax egg
Form into patties
Chill the patties briefly
Pan-fry, bake, or grill until firm and browned
Serve on buns with toppings and sauce