Italian sausage and peppers—it doesn’t get any more iconic than this sweet and spicy dish bursting with summer vegetables and juicy Italian sausage. Perfect for big family get togethers or potlucks; slice up some crusty bread and everyone can dish up their own, just the way they like it.
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.
Transfer to a cutting board. When cool enough to handle, slice into 1-to-2 inch pieces.
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.
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.
Season to taste with salt and pepper. Serve on rolls if desired.