Drain your black beans from the tins and pat dry with a kitchen towel. Alternatively if using dried black beans, boil them until cooked through and drain
Place the red pepper, carrot, jalapenos and walnuts in a food processor and pulse till finely minced
Transfer the mixture to a large mixing bowl and add in the tomato puree, mushroom sauce, vinegar, black beans, salt, garlic, cumin, paprika and dried parsley. Mix to combine
Roughly mash the mixture whilst making sure to leave some of the black beans whole for texture
Add plain flour and oats, and mix to combine
Form burger patties to desired size and pan fry in 2-3tbsps of oil for 3-4 minutes on a medium heat. Flip the burgers over and continue to cook for a further 3-4 minutes. (Baking and grilling instructions are in the recipe notes)
Layer the burgers up in your buns with mayonnaise, lettuce, red onions and tomato