You can find these dumpling makers everywhere, but I like JapanBargain on Ebay. Free shipping on just about everything, and every japanese kitchen utensil I ever need can be found in their store. The dumpling maker comes with a handy little spatula, to deposit just right amount of filling.
Before starting, set your steamer up. Basically, you need something to hold the dumplings up and out of the simmering water. You could set a plate on top of a cup inside a covered pot of simmering water. Or buy a steamer plate, again Japan Bargain has these, or use the steamer insert that came with your pan set. Line the steamer with cabbage leaves, these keeps them from sticking and I also feel it adds an authenticness, but that just maybe my imagination. Put the heat on low-med to start the water heating, by the time you are done pressing the dumplings, it should be simmering.
Merry's Dumpling Filling
1 lb of skinless, boneless chicken breasts
1/2 lb of shrimp, peeled, cleaned and tails off
1 bunch of green onions, chopped
1 can of water chestnuts, chopped small
4 tbsp or more of soy sauce
2 tbsp of oyster sauce
2 tsp sesame oil
1 tbsp rice vinegar
You will also need: savoy cabbage leaves for the steamer
Sweet Chili Sauce
Peanut Butter (optional)
Process the chicken and shrimp until minced thoroughly. Add the rest of the ingredients and process until well mixed.
Proceed as above until all your filling is gone, I was able to make quite a bit, I used about 55 or so dumpling skins. If you don't have the round skins, you can use square wonton wrappers, just cut them into circles with a cookie cutter, or heck keep them square, just set them on the diagonal in the press.