Peel and finely chop onion. Peel and crush garlic. Heat oil in a large frying pan. Gently fry onion and garlic for 5 minutes, stirring occasionally, until softened but not browned

Meanwhile, cut a cross in the top of each tomato and put in a bowl. Cover with boiling water and leave for 1 - 2 minutes. Drain, plunge into cold water, then remove skin. Chop finely, removing any hard cores.

Add tomatoes, tomato puree, sugar and herbs to onion mixture. Season and add 150ml/ 1/4 pint stock. Bring to boil. Cover. Simmer for 30 minutes, stirring occasionally. In a separate pan, bring remaining stock to boil. Simmer ravioli in 2 batches for 3 minutes per batch, or until cooked. Keep warm. Add ravioli to tomato sauce and stir, to coat. Divide between 4 plates and sprinkle with Parmesan. Season with pepper and garnish with basil leaves.