Preheat oven to 170°C.
Mix the spices.
Rub the meat with oil, season with salt and pepper, then rub with spice-mixture.
Heat the oil in a large, heavy-based oven-proof dish or casserole dish and brown the meat on all sides.
Meanwhile, slice the onions then sprinkle around the meat, pour the wine & stock over, then bring it to the boil. If the liquid doesn't cover the meat, add more stock.
Cover the dish with a lid, and put it in the oven. Cook for 2-3 hours.
In the meantime, peel and dice the potatoes. Add these to the lamb for last 30 minutes, mix well with the sauce.
When the potatoes & the meat are tender, and the sauce is thick and shiny, the dish is ready. Using 2 forks, shred the meat into chunky pieces and toss well with the sauce.