Preheat the smoker to 300 degrees Fahrenheit according to manufacturer's instructions.
Prepare the bell peppers by cutting off the tops and removing the stems/seeds. Save the top of the pepper to dice and add into the stuffing mixture.
In a large pan over medium heat, brown the ground beef and ground sausage together.
Once cooked, drain the meat and set aside.
Sauté the onions and diced pepper tops with a splash of olive oil for about 5 minutes.
Add the garlic and continue to cook until the vegetables start to soften, about 3 minutes.
Combine the meat and the vegetables in a bowl and stir in half of the shredded cheese. The other half of the shredded cheese will be used to top the peppers.
Fill each bell pepper with the ground meat and vegetable mixture.
Place the peppers in the smoker, making sure to set them on the grates so they won’t fall over while cooking.
Smoke the peppers for about 50 minutes, they should be slightly brown and tender, but the peppers should still have a bit of firmness. You don’t want them to be soggy.
Top the peppers with the rest of the shredded mozzarella cheese and smoke for another 10 minutes, or until the cheese has melted.
Carefully remove peppers from the smoker, garnish with cilantro or parsley, and serve.