In a large skillet, add 1 tbsp of olive oil over medium heat. Once warmed, add the 4 Italian sausages into the skillet. Heat for about 5 minutes until the skin is brown on one side. Then, flip the sausage over and heat for another 5 minutes. The sausages do not need to be cooked all the way through at this point.
Remove the sausage from the skillet and set aside.
Add the remaining 2 tbsp of olive oil into the skillet and warm again over medium heat.
Add the 4 sliced bell peppers and 1 sliced onions into the skillet.
Saute for about 10-15 minutes until the peppers and onions are mostly soft, but still have some structure.
Add the 30 oz of tomato sauce into the pan along with the 1 tsp salt, ½ tsp pepper, and 1 tsp garlic powder. Add a lid and cook, stirring occasionally, for 10 minutes.
In the meantime, slice the sausages into ½” - 1” pieces. The sausage will still be pink in the middle.
Once the 10 minutes is up, remove the lid from the skillet and add the sausage pieces into the sauce. Stir to combine.
Continue cooking, with the lid off, for about 10-15 more minutes, until the sauce has reduced a little and the sausages are cooked all the way through (they should reach an internal temperature of 160 degrees Fahrenheit).
Serve and enjoy!