A subject which causes heated debate - I can only pass on two widely differing recipes given to me by two highly esteemed Irish women.
The first and most pure consists only of potatoes, onions and lamb (or mutton if you can get it) chops, best end of neck, or if following a low fat diet, trimmed stewing pieces. Peel and slice the vegetables, add the lamb and seasonings. Cover with cold water. Bring to the boil on the top, transfer to a warm oven and allow to cook for several hours or until suitably tender. Serve sprinkled with plenty of finely chopped parsley to improve the colour.
The second is basically the same, but includes carrots, and the gravy is thickened with pearl barley which has a delightful chewy texture. A stock cube isn't a bad idea.