01 - In a large mixing bowl, mash the black beans with a fork or potato masher until coarse but not pureed, leaving some texture for a hearty bite.
02 - Add the grated carrots, chopped mushrooms, diced red onion, corn kernels, minced garlic, parsley, rolled oats, breadcrumbs, smoked paprika, ground cumin, salt, and black pepper to the bowl with the mashed beans.
03 - Add the egg (or prepared flax egg) to the bowl and mix thoroughly until all ingredients are evenly distributed and the mixture holds together when pressed.
04 - Divide the mixture into 4 equal portions and shape each into a burger patty approximately 1 inch thick, ensuring even thickness for uniform cooking.
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 oven until lightly golden for added texture and crunch.
07 - Layer each bun with a cooked patty and top with lettuce, tomato slices, pickles, ketchup, or your preferred toppings. Serve immediately.