Prepare the sweetbreads as follows: wash and soak in cold water for 1–2 hr. until free from blood. Put into a pan, cover with cold water, bring to boil and simmer for 3–5 min., then plunge into cold water. Discard fat and skin and any gristle. Press between two plates to retain shape.
Melt the fat in a stewpan or meat-tin, add the sliced vegetables and fry for about 10 min., then add the bouquet garni, peppercorns, salt and pepper and almost cover with stock. Place the sweetbreads on top of the vegetables and cover with greased greaseproof paper. Bring to the boil, baste the sweetbreads well and cook in a moderate oven (350° F., Gas 4) for about 1 hr. with the lid on. Add more stock as necessary and baste occasionally. Meanwhile cut a croûte of Bread