Brown the sausage. Heat a large deep skillet or Dutch oven over medium-high. Add the full pound of sausage and break into bite-size crumbles. Brown for 5–7 minutes. Spoon off excess rendered fat, leaving a little to cook the vegetables. No automatic extra oil.

Soften the vegetable base. Reduce to medium. Add onion, carrot, and celery and cook 7–9 minutes, stirring, until softened. Add a little olive oil only if the pan is dry. Give the onion time to soften rather than rushing this step.

Bloom garlic, chili, and tomato paste. Add garlic, oregano, and 1/4–1/2 teaspoon chili flakes. Stir for 30 seconds. Stir in tomato paste and cook for 1 minute without scorching.

Simmer the sauce. Add crushed tomatoes, diced zucchini, and black pepper. Scrape up browned bits, using a splash of water if necessary. Simmer gently uncovered for 15–20 minutes, stirring occasionally, until zucchini is tender and the sauce is thick but spoonable. Pork sausage must reach 160°F (165°F if using poultry sausage). Taste before adding salt or more chili. No wine, sugar, or cream.

Boil pasta separately. While sauce simmers, cook rigatoni in salted water according to its package, stopping just shy of your preferred doneness. Reserve a mug of pasta water before draining. Do not cook the pasta directly in this sauce.

Toss and serve. For immediate eating, toss the desired pasta portion with sauce over medium heat for 1–2 minutes. Add reserved pasta water a little at a time until sauce clings to the tubes, not enough to turn soupy. Finish with optional light cheese.

Save leftovers without soggy pasta. Keep unused sauce and pasta separate. Refrigerate promptly and use within 3–4 days, or freeze extra sauce. For best texture, cook fresh pasta for later portions. The original Rigatoni recipe remains unchanged.