01 - Place the drained and rinsed black beans in a large mixing bowl. Use a fork or potato masher to coarsely mash them, leaving some texture intact—avoid turning them into a complete puree.
02 - Add the grated carrots, chopped mushrooms, diced red onion, corn kernels, minced garlic, chopped parsley, rolled oats, breadcrumbs, smoked paprika, ground cumin, salt, and black pepper to the bowl with the mashed beans.
03 - Crack the egg into the bowl (or add your prepared flax egg). Stir 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 so they hold their shape.
05 - Heat the olive oil in a large skillet over medium heat. Once the oil shimmers, carefully place the patties in the pan. Cook for 4 to 5 minutes per side until both sides are golden brown and the patties are cooked through.
06 - While the patties finish cooking, toast the burger buns face-down in a separate skillet or under a broiler until lightly golden.
07 - Place each cooked patty on a toasted bun. Layer with lettuce leaves, tomato slices, pickles, and your preferred sauces. Serve immediately.