Preheat oven to 350° F. Add the bell peppers to a 13 x 9 in. baking dish, facing up. When the oven has preheated, add the baking dish to the oven for 20 minutes.
You may need to cook the meat in one pan and the veggies in another pan, unless you have a very large saute pan. Add 1 tbsp. of the cooking fat to a large saute pan over med.-high heat. Add onions and garlic and cook for 3-4 minutes until fragrant. Add in celery, carrots, and cauliflower rice. Stir and continue to cooking over med.-high heat. Add sea salt and pepper. Add in one jar of Otamot Tomato Sauce. Stir and cook for 20 minutes until veggies are cooked through.
While the veggies are cooking, add the remaining cooking fat to a separate skillet on med.-high heat. Add in the ground bison and season with Italian seasoning. Continue cooking for about 10 minutes. Add in the second jar of Otamot tomato sauce, stir, and cook until meat is done.
Combine the ingredients from both pans in the larger skillet or in a large bowl. Stir to combine.
Remove the par-baked bell peppers from the oven. Using caution with the hot peppers. Add stuffing to each pepper - they will likely be overflowing - that's ok. Top with grated mozzarella cheese.
Place the baking dish in the oven and cook for 15 minutes until cheese is melted. Serve and enjoy!