The day before cooking, put the cumin and coriander seeds in a dry pan and toast until they are slightly coloured and aromatic.
Remove to a board and crush them with the blade of a knife. Crush the juniper berries and mix with the spices and the salt. Rub the mixture over the duck, scatter with thyme, rosemary and sliced garlic and chill for 24 hrs, turning two or three times as they marinate.
Next day, heat oven to 150C/130C fan/ gas
Wipe the duck with kitchen paper and pat dry, but dont wash off the marinade. (The salt extracts the water from the meat cells, which will be reinflated with fat as the duck cooks gently. If you wash it, you will simply reinflate the cells with water.)
Put the duck in a cast-iron casserole and cover with the goose fat or duck fat.
Add the bay leaves and peppercorns and cook for about 2 hrs, or until the meat is almost falling away from the bone. You can store the duck very simply by placing it in a pudding bowl, covering it with the fat and keeping it in the fridge: as long as it stays covered with fat it will last for weeks.
To cook, remove the confit duck legs from their fat. Put an ovenproof frying pan on the stove until it is hot.
Add the duck legs, skin-side down, and cook for 4 mins. Turn the legs and transfer the pan to the oven for 30 mins, until crisp.
