Chop the cabbage finely. Add it to a mixing bowl. Sprinkle salt over it to wilt the cabbage. Stir.
Mince garlic, shred carrot, and add to mixing bowl.
Add mackerel to mixing bowl, crush into pieces if needed.
Add some more salt, pepper, curry powder, and oyster sauce. Stir thoroughly.
Put something on the bottom of your steamer so the dumplings won't stick. Either a veggie leaf or a liner.
Put a spoonful of filling in the middle of your wrapper. Wet the edges of the wrapper, bring them all to the top and press together. Put in the basket and repeat until your are out of filling, wrappers, or room in the steamer.
Heat an inch of water over medium. Once it starts steaming/bubbling, carefully add your steaming basket. Steam it for 10 minutes, or until wrappers look done.
Serve with peanut sauce and fresh lime slices and enjoy!