Serves 62 to 3 tbsp (30 to 40 mL) vegetable oil
Lightly coat a large, wide ovenproof saucepan or Dutch oven with oil and set over medium-high heat. When oil is hot add shanks to pan, a few at a time. Brown lamb shanks on all sides. Add more oil to pan as needed. Remove prepared shanks to a plate and set aside.
Meanwhile, peel then slice onions onto rings, about ½ inch (1 cm) thick. Peel and finely chop garlic. Set aside. Heat oven to 350F (180C).
After removing shanks from pan, reduce heat to medium. Add onions, garlic and a little more oil to pan, if needed. Cook, stirring often, until onions are soft, about 5 minutes. Sprinkle oregano, chili powder, and black pepper into pan. Stir to combine.
Return shanks to pan. Pour in wine and beef broth. Increase heat to high and bring to a boil. Remove from stove. Cover with light or foil and place in preheated oven. Oven braise for 2 to 3 hours, or until fork tender.