Juice the sour oranges, and combine with the garlic, onion, oregano, bay leaf, and white wine in a large bowl. Place meat into the marinade, cover, and refrigerate for 2 to 4 hours. In a large pot, heat oil over medium high heat. Place meat into the pan, and sear on all sides. Decrease heat to low. Pour marinade over meat in the pan, and cover. Cook until the meat is fork tender, about 3 hours; add water to the pot if necessary to keep the meat from scorching.