1.Cook pasta in large saucepan of boiling water until tender; drain.
2.Meanwhile, heat half of the oil in medium frying pan; cook onion and garlic, stirring, until onion is soft. Stir in tomato and stock; cook, covered, about 10 minutes or until tomato is soft.
3.Combine pasta with tomato mixture and remaining oil in large bowl. Serve pasta topped with cheese and basil; drizzle with vinegar.
You can use ravioli instead of the tortellini, if you like.Note