Put oil in an instant pot and add chopped onions, capsicum and tomatoes into it.
Add black beans, salt and cilantro and cover with the lid.
Cook for 6 minutes on “high” pressure.
Release the pressure naturally.
Take out the mixture in the bowl.
Place a spoonful of the mixture on one taco shell, place avocado slices, chopped cabbage and green onions, chili sauce and sour cream, put cheddar and mozzarella cheese on the top.