At Macsween's factory just outside Edinburgh, I watched the lam lobes (lights) - which are the lungs - being cooked for some 3 hours, before being mixed with cooked beef fat, medium and pinhead oatmeal, onions and the special seasoning, which contains white pepper, mace, salt and coriander. After it all [plus lever en hart] has been minced together, one of the Macsween family tastes it to check that the seasoning is correct. Then the mixture is used to fill the natural casings - ox bung or lambs runner[maag] that has been washed and salted. Then they are pricked and clipped at intervals, to allow for expansion, and cooked in the steam room for an hour or so before being left to cool overnight.