Make the patties. In a large bowl combine all the ingredients. Form patties with your hands and pan fry on both sides for 5-7 minutes until golden.
Assemble the burgers. Spread mashed avocado on the bottom of the burger bun, continue with black bean patties, then cheese, tomato slices, another pattie, baby spinach and place the top of the bun on and insert a stick skewer through the burger. Repeat until you have 4 burgers ready. Enjoy.