This is a wonderful alternative to the normal gravy that accompanies a roast and is particularly good with game meats.
1. Place chestnuts, carrot, celery, leek, onion, garlic, loose spices and butter/oil in a saucepan. Fry together until the mixture starts to brown.
2. Add water and wine, bring to the boil and simmer with lid on for 20-30 minutes. The chestnuts should be tender but not fall apart.
3. Strain stock into a clean pan, pick out chestnuts from vegetables.
4. Discard remaining vegetable mixture. Mix yeast extract, cornflour, and tomato purée to a paste with 4 tbsp cold water and stir into the hot chestnut stock.
5. Bring to the boil stirring frequently; add the reserved chestnuts and simmer for 5 minutes until thickened.