01 - If using flaxseed, combine ground flaxseed with water in a small bowl and let rest for 5 minutes until a gel forms.
02 - Heat 1 tbsp olive oil in a skillet over medium heat. Sauté onion, carrot, bell pepper, and garlic for 4–5 minutes until softened. Stir in spinach and cook until wilted. Remove from heat.
03 - In a large bowl, mash black beans with a fork or potato masher, leaving some texture for a hearty bite.
04 - Add sautéed vegetables, oats, breadcrumbs, tomato paste, smoked paprika, cumin, salt, pepper, and the flax egg (or regular egg) to the mashed beans. Mix thoroughly until well combined.
05 - Shape the mixture into 4 equal patties, pressing firmly so they hold together.
06 - Heat remaining olive oil in the skillet over medium heat. Cook patties for 4–5 minutes per side until golden brown and cooked through.
07 - Serve on toasted buns with your favorite toppings such as lettuce, tomato, avocado, or pickles.