Olive oil for frying
1 large onion, peeled and finely chopped
1 garlic clove, crushed with 1/2 tsp salt
3/4 kg (1 1/2 lb) minced beef
2 tbsp spoons tomato puree
396 g (14 oz) can tomatoes
Approx. 300 ml (1/2 pint) chicken stock
1 tsp spoon sugar
1 tbsp red or white wine vinegar
1 tsp spoon...