In a pot on medium heat, add oil and sear the Italian sausage for 3 minutes on each side until browned. Set aside.
In the same pot, sauté pepper and onions for 5 minutes. Add garlic and sauté for another minute.
Slice the sausage into 1 inch pieces and add to the pot along with pasta, crushed tomatoes, Italian seasoning, red pepper flakes, salt and pepper, and water. Mix until combined.
Cover and bring to a boil then cook until the pasta is al dente. Stir occasionally to prevent the pasta from sticking to the bottom of the pot. Check for doneness around 15 minutes. If the sauce is too thick, mix in ¼ cup more water until the pasta is cooked.
Serve with pecorino romano or parmesan cheese. Garnish with fresh basil and oregano if desired.
Notes
Taste the pasta for doneness. Cooking times will vary if you use a different pasta shape like penne, shells, rotini, or farfalle.