88 Veal Kidney in its Fat

Name: Veal Kidney in its Fat
Yield: For four people
Cuisine: French
Ingredients: 350 g (12¼ oz) each of carrots and onions and 150 g (5¼ oz) white part of leeks, peeled and cut in 1 cm dice; 4 veal kidneys encased in their natural suet; 1½ tablespoons olive oil; 1 litre (1¾ pints) Algerian red wine or Spanish red wine; 8 tablespoons stock made by dissolving ¼ chicken stock cube in 8 tablespoons water; 1 unpeeled clove of garlic, crushed; 2 tablespoons chopped shallot; 1 teaspoon caster sugar; 1 bouquet garni; 1 teaspoon Dijon mustard; 25 g (1 oz) softened butter