Meat filling

In a frying pan, sauté 1 small onion, 2 carrots and 1 celery stalk, all finely chopped, in 3 tbsp/45 g butter. When soft, add ½ oz/15 g dried mushrooms, soaked and chopped, and 1 lb/500 g ground lean beef. Cook, stirring, until the meat is brown, 4-5 minutes. Add ½ cup/125 ml Marsala and boil to evaporate the liquid. Add 2 tbsp tomato paste and enough of the mushroom soaking liquid to dissolve