PREHEAT oven to 400 degrees and line a baking sheet with parchment paper. Place bell peppers on baking sheet and bake 10 minutes.
WHILE peppers cook, heat a large skillet over medium heat and add olive oil. Add steak, onion and mushrooms to skillet and cook 5 minutes until onions begin to soften. Remove from heat and stir in coconut aminos, garlic powder, sea salt and black pepper.
REMOVE peppers from oven and fill each pepper with steak mixture. Return to oven on baking sheet for 10 minutes. Turn oven to broil and place a slice of cheese on each pepper. Broil 3-5 minutes until golden brown and bubbly. Serve hot. NOTE! Watch the broiler folks! Sometimes it might only take 3 minutes- if I were you I’d check after 2 minutes, then every minute after that.