Heat the oil in a large pan over a medium heat. Cook the onions and peppers until soft and charred (about 8 minutes). Add the black beans, and Old Bay Seasoning and cook for a further 3 minutes until warmed through.
Melt the butter in a pan and gently cook the beaten eggs until they are soft scrambled eggs.
Spread each tortilla with a spoonful of sour cream and salsa, then a spoon of the black bean mixture and top with scrambled egg and sliced avocado.