fresh basil leaves, to serve (optional)
1 small onion, finely chopped
400g/14oz tin chopped tomatoes
½–1 tsp dried chilli flakes, according to taste
275g/9¾oz dried spaghetti
½ tsp dried mixed herbs or dried oregano
1 tbsp olive oil
2 tbsp tomato purée
grated Parmesan, to serve (optional)
4–6 good-quality sausages (300–400g/10½–14oz)
150ml/5fl oz red wine or water