Bring 3-4 l salted water (1 teaspoon salt per litre) to the boil. Peel and finely chop the onion. Clean the chilli, cut lengthwise, remove seeds, wash and chop finely. Mix chilli and onion.
Cook the pasta in boiling salted water according to the instructions on the packet. Fry sausage meat in hot oil until finely crumbly. Add chili mix and tomatoes, bring to the boil. Season with salt, pepper and 1 tsp. oregano. Simmer for about 5 minutes.
Drain the pasta. Wash and chop the basil. Mix both with the sauce.