Pare the fat from the ham and mince with the chopped parsley and mustard. Spread thickly on the meat.
Slice the unpeeled apples
Place the ham in the center of a pan, with the apples and then the potatoes in a ring around it. Add the hot water, and sprinkle with the brown sugar.
Bake in a 325-350° oven, basting often, until the potatoes are tender. [This bakes faster if put in a shallow casserole and covered for the first half-hour.]