01 - Mix ground flaxseed and water in a small bowl and set aside for 5 minutes until thickened.
02 - In a large bowl, mash the black beans with a fork or potato masher until mostly smooth with some texture remaining.
03 - Add oats, gluten-free breadcrumbs, red onion, garlic, flax egg, tomato paste, smoked paprika, cumin, chili powder, salt, and black pepper to the mashed beans. Stir until fully incorporated.
04 - Shape the mixture into 4 equal patties, pressing firmly to hold their shape.
05 - Heat olive oil in a skillet over medium heat. Cook patties for 5 to 6 minutes per side until browned and heated through.
06 - Combine vegan mayonnaise, chopped chipotle peppers, adobo sauce, lime juice, and salt in a small bowl. Mix well and adjust seasoning to preference.
07 - Optionally toast the burger buns until lightly golden.
08 - Spread chipotle mayo on each bun, add a black bean patty, then layer with lettuce, tomato, red onion, and pickles. Serve immediately.