Step 1

In a large skillet over medium-high heat, add oil and heat until shimmering. Add sausages and cook until browned on all sides (sausages will not be fully cooked), about 5 minutes.

Step 2

Transfer to a cutting board. When cool enough to handle, slice into 1-to-2 inch pieces.

Step 3

Reduce heat to medium. To the skillet, add onions and peppers. Cook until softened, about 3 minutes. Stir in garlic until fragrant, about 30 seconds.

Step 4

Return sliced sausage to pan. Add diced tomatoes, tomato paste, basil, oregano, and red pepper flakes (if using). Bring to a simmer and cook until sausage is cooked through and sauce has thickened, about 5 to 10 minutes.

Step 5

Season to taste with salt and pepper. Serve on rolls if desired.