To “rice” the cauliflower – cut raw cauliflower into bite-size pieces. Place cauliflower in the food processor. Pulse for about seven 1-second pulses until cauliflower pieces are about the size of rice.
Preheat oven to 375ºF and adjust rack to middle position. Melt coconut oil in a large skillet over medium heat. Add onion whites and beef and cook until beef is no longer pink, about 5-7 minutes. Make a well in the center of the pan and add the cumin and garlic. Cook in the middle of the pan until fragrant, about 45 seconds and then stir into beef mixture. Add riced cauliflower, chiles, 1 cup cheese and sea salt to pan and stir until all ingredients are incorporated. Remove from heat.
Place peppers cut side up in a large baking dish. Divide filling mixture evenly among peppers. Pour 1/2 cup water in the bottom of the pan and then cover peppers with a layer of parchment paper followed by a layer foil (I do this so the aluminum doesn’t touch the food). Bake for 25 minutes and remove from oven. Remove the foil and parchment and top each pepper with a bit of sour cream, salsa and remaining 1 cup cheese. Bake for an additional 10 minutes until cheese is bubbly and golden brown. Serve.