Method After roasting a joint of meat, lift it out of the tin, and pour away all excess fat. Fill the tin with potatoes, sliced thickly, lengthways, and cover with a layer of finely chopped onion. Sprinkle with a little salt, pepper and flour and cover with boiling water. Roast in a hot oven until the potatoes are golden brown. A meal prepared for swper chwarel (the evening meal) in the slate-quarrying districts of north Wales. Y Fach-wen, Caernarvonshire.