In a large bowl combine lamb mince, garlic, ginger, mushrooms, water chestnuts, green onions, celery, coriander, light soy and sesame oil.
Place a wrapper on a clean work surface. Spoon a heaped teaspoon of lamb mixture on to the centre of the wrapper. Brush the edge with a little water. Fold over to enclose the filling. Use your fingertips to pleat the edge 4 to 5 times to seal. Set aside on a plate covered with a tea towel. Repeat with remaining mix and wrappers.
Place a large steamer basket lined with baking paper over a large pot of simmering water. Steam dumplings, in batches, for 7 to 8 minutes or until translucent and lamb is cooked.
Serve dumplings with plum sauce, coriander sprigs, steamed gai lan and brown rice.