01 - In a large mixing bowl, mash the black beans with a fork or potato masher until coarse but not fully pureed. Some texture should remain for a hearty bite.
02 - Add the grated carrots, chopped mushrooms, diced red onion, corn kernels, minced garlic, parsley, rolled oats, breadcrumbs, smoked paprika, cumin, salt, and pepper to the bowl with the mashed beans.
03 - Add the egg (or prepared flax egg) to the bowl. Mix thoroughly until all ingredients are evenly distributed and the mixture holds together when pressed.
04 - Divide the mixture into 4 equal portions. Shape each portion into a patty approximately 1 inch thick, pressing firmly to compact the mixture.
05 - Heat olive oil in a large skillet over medium heat. Cook the patties for 4 to 5 minutes per side until golden brown and cooked through.
06 - Toast the burger buns in the skillet or under a broiler until lightly golden.
07 - Layer each bun with a patty, lettuce leaves, tomato slices, pickles, and your favorite sauces. Serve immediately.