Clean the cabbage, chop it, and put it in a large non-reactive pot with salt Set it aside and let it sweat out water for 45 min or so (you can prepare this ahead).
If you're using a meat grinder, feed the shrimp, pork, garlic, onions, and ginger through the meat grinder, getting everything to be a smooth, yet chunky mixture. If you're using a food processor, you're going to half way freeze the meat, and chop each ingredient on it's own, and then mix them in a pasta bowl. Traditionally, all these ingredients are minced and chopped using a large cutting board and a cleaver. However you do it, it's up to you.
Put the meat and veggie mixture into a a large bowl. Add the salt, soy sauce, egg and sugar to the mixture.
In a heavy skillet, heat up the oil. Add the spice powders and toast the spices. Pour this mixture hot over the meat mixture in the bowl, and stir inches.
Drain the cabbage, rinse it and drain again. Mix it in to the meat mixture.
(Optional step) Make the dumpling wrappers: mix together 1 1/2 cup flour and pinch of salt and then slowly add just enough water to result in a springy dough. Knead it a lot to make the gluten stringy and strong. Roll the dough out into a long rope, cut the rope apart into ping pong ball sized pieces. Flatten the pieces out into small flat discs, and flour a table or cutting board, and roll them out using a beer bottle or small rolling pin. As you make them, hand them to the person wrapping the dumplings. Or just buy the pre-made wrappers.
Wrap the dumplings in the dumpling skins, pinching together the sides and tucking in the ends.
Cook the dumplings: boil a pot of water. Drop the dumplings in, they are ready when the float to the top of the pot. Don't boil too many at once, or they'll stick together. Scoop them out with a strainer, so you can use the water for the next batch.
Serve with soy sauce, dipping sauce, raw garlic (for true Northern Chinese style eating!), chili sauce, or cut up green onions.