Steamed Stuffed Onions

Cut the bases off the onions so they sit upright. Core out the middles, leaving outer shells of 3 to 4 layers. Reserve the middles for some other use. Place the onion shells in a bowl of cold water until needed. In a mortar, pound the peppercorns, garlic and coriander roots together into a juicy paste. Place the pork and crab meat in a bowl and add the contents of the mortar, mixing everything