Super-Easy Sausage and Peppers

Ingredients (5)

• + 7 sweet Italian sausages, or more to taste, removed from the casings and cut into bite-size pieces add to pantry
• + 1 tablespoon olive oil, or more to taste add to pantry
• + 1 large sweet onion, halved and sliced add to pantry
• + 2 (14.5 ounce) cans tomato sauce add to pantry
• ✓ 3 green bell peppers, sliced