Place the ground beef, 1/4 cup steak sauce, fajita seasoning, and diced onion in a medium bowl. Shape the mixture into 8 patties.
Place 1 slice of cheese, green peppers, and mushrooms over 4 other patties. Then, apply the 4 layers of previously applied paste, pressing down gently,
sealing the edges tightly so that the paste does not spill out. Heat the outdoor grill for a low flame and put some oil on the grill grate.
Then stand the patties on edge on the grill and brown them lightly on both sides. When they begin to brown, spread with the remaining steak sauce.
The juices have run clear When the meat is cooked through, sprinkle the strips with the remaining 4 cheeses and allow them to melt. Serve on buns or just as a patty.