1Heat oven to 325°F. Using long narrow knife, cut about twelve 2-inch deep slits in pork. Place onion wedge in each slit.
2In medium bowl, mix rub ingredients to form a paste. Using hands, rub entire pork shank with paste, working rub into meat. Place pork on large rack in roasting pan.
3Bake 6 1/2 to 7 hours, basting with pan juices after 2 hours, every 30 minutes, until meat reaches internal temperature of 145°F. Let stand about 20 minutes before cutting into thin slices.