1. Heat the oil in a saucepan, add the onion and gently fry 3-4 minutes until softened.
2. Add the remaining ingredients (except the spaghetti), stir through and allow to cook for 10 minutes.
3. Meanwhile, cook the spaghetti in boiling water according to the pack directions.
4. Drain the spaghetti and stir into the sauce. Delicious served with buttery garlic bread and a fresh green salad.