Heat the oven to 200°C. Coat the bottom of a roasting dish with olive oil. Slice the potatoes thinly, heat some olive oil in a large frying-pan, and sauter the potatoes in several batches, turning them so that they are just translucent and starting to brown.
Arrange them in layers in the roasting dish, interspersing them with the herbs, salt and pepper and cloves of garlic. Pour on the stock and the white wine. Place the lamb on top of the potatoes, anoint it with olive oil and butter, and roast for it for between 1 hour 30 minutes and 1 hour 40. Baste the lamb occasionally. Let the dish rest, covering the meat with foil, for 15–20 minutes. Remove the joint to carve it, and dish out succulent potatoes from the roasting tin. Serve on very hot plates.