01 - In a small bowl, combine the ground flaxseed with water and let it rest for 5 minutes until a gel-like consistency forms.
02 - Heat 1 tbsp olive oil in a skillet over medium heat. Add the onion, carrot, bell pepper, and garlic, and sauté for 4–5 minutes until softened. Stir in the spinach and cook until wilted. Remove from heat and set aside.
03 - In a large mixing bowl, use a fork or potato masher to mash the black beans, leaving some texture for a hearty bite.
04 - Add the sautéed vegetables, oats, breadcrumbs, tomato paste, smoked paprika, cumin, salt, pepper, and the prepared flax egg (or regular egg) to the mashed beans. Mix thoroughly until all ingredients are evenly incorporated.
05 - Divide the mixture into 4 equal portions and shape each into a firm patty.
06 - Heat the remaining olive oil in the skillet over medium heat. Cook the patties for 4–5 minutes per side until golden brown and cooked through.
07 - Serve the patties on toasted buns with your choice of toppings such as lettuce, tomato, avocado, or pickles.