Bring a large pan of water to the boil, and cook the pasta for approximately 12 minutes.
Meanwhile heat the oil in a large frying pan, then add the onions and cook until softened, then add the sliced smoked sausage and stir.
When the pasta is cooked, drain and put it in with the onion and sausage, then add the tomato soup, and stir everything together until the soup has heated through. Add salt to taste.