Thinly slice tomato and onion Mince onion and garlic with salt and pepper. Mix with beef and pork and form 2" patties. Heat oil in a non-stick pan and cook patties, 4 - 6 minutes on each side. Mix Gochujang sauce and mayonnaise and set aside Toast buns (if desired) Serve on the buns with mustard green/lettuce, tomato, patties, onion and Gochujang mayo sauce.