Heat the olive oil in a deep frying pan and gently cook the onion, covered, for about 5 minutes until soft.
Stir in the garlic and chilli; cook for a minute. Increase the heat, add the tomatoes and wine (or water or stock), cover, bring to the boil and simmer gently for 10 minutes. Remove the lid and bubble for a further few minutes. Season to taste with salt, black pepper and a pinch of sugar.
Add the prawns and half the parsley, cover and cook for 2 minutes until the prawns are cooked through.
Crumble over the feta and sprinkle with the remaining parsley; leave to stand for a minute. Serve with the toasted bread, drizzled with olive oil, and the lemon wedges.
