How To make Crusty Roast Lamb (Uaineoil Faoi Chrusta) (Irish)

1 Shoulder of lamb, 4 lb
1 c Fresh breadcrumbs
Pinch mixed herbs 2 tb Butter, soft
1 1/2 lb Potatoes, peeled, sliced
1 Lg onion, diced
1 Lg cooking apple*
10 oz Chicken stock
*Peeled, cored and sliced. Wipe the lamb over, and cut criss-cross slits around the top. Mix together the breadcrumbs, herbs, butter, salt and pepper. Rub the mixture onto the top of the meat, pressing down well so that it sticks. Fill the bottom of the roasting pan with the vegetables and apple, mixing them and the seasoning well. Put the joint on top, then pour the stock into the pan, but not over the meat. -- Cover loosely with a piece of foil and bake at 400 F for half an hour. Then lower the heat to 350F, and cook for a further 20-25 minutes to the pound. Take off the foil for the final half hour, and check that the vegetables are nearly cooked. Finish the cooking without the foil, to let the top get brown and crusty.