Heat the oil in a saucepan and gently cook the onion and garlic until softened. Stir in the tomatoes, chilli flakes, balsamic vinegar and sugar. Bring to a simmer and cook slowly for 45 minutes-1 hour. Stir in the basil and season with salt and pepper. This can be left chunky or blended in a food processor for a smooth sauce.
Serve spooned over cooked pasta with plenty of parmesan cheese.
Substitute the following as you prefer:
- 250g/9oz tub of mascarpone or cream cheese, either alone or with strips of smoked salmon
- chopped black olives and marinated artichokes
- fried bacon and mushrooms
- prawns, capers and chopped parsley
- chopped chicken, red onion and red peppers, fried in olive oil
- fried slices of chorizo sausage, chopped black olives and pieces of mozzarella cheese