Place a cast iron skillet directly over the heat, add a little oil and saute the diced peppers, onion, and garlic for about 15 min. Move the skillet to a cooler area of the grill and add the entire jar of marinara sauce to the skillet. Put the bratwurst sausages directly over the flame. Close the grill dome and cook the sausages for about 3 minutes a side until they are cooked. After they are cooked add the sausages to the skillet and stir everything around. Keep the bratwurst in the skillet along with the peppers and onions for another 15 to 20 minutes.

Wrap the Wheat Grinder Sub rolls in aluminum foil and place them directly on the grill grate. After a minute or so, turn the roll around. This will get the roll a bit crispy and very warm. Open up the foil and lay a bratwurst sausage in the roll and generously top with the marinara sauce mixture. Top the sub with some shredded mozzarella cheese and serve.