1. If you are baking your gyoza instead of pan-frying (instructions for both methods below), preheat your oven to 400 F (200 C).
2. In a large bowl, combine the flour, salt, and water while mixing with your hands until a dough starts to form (Note: Because I live in a fairly dry climate, I usually need to end up using about 3/4 c water. The end result should be fairly elastic, but not too wet).
3. Onto a flat surface, sprinkle some flour. Knead the dough on it for about 10 minutes until it becomes smooth and elastic. Cover the dough with a damp cloth or plastic wrap and let it rest at room temperature for at least 30 minutes.
4. After resting, divide the dough into 36-38. Work with one portion at a time, keeping the others covered to prevent drying out. Take one dough ball and flatten it with your palm. Using a rolling pin, roll it into a thin circle, about 3-4 inches in diameter.
5. Repeat the rolling process with the remaining dough balls and dust each wrapper lightly with flour to prevent sticking and stack them as you go.
6. Begin making the gyoza filling. To a bowl, add all of the filling ingredients (except for the cheese) and mix to combine with your hands.
7. To a wrapper, add about 1 1/2 tbsp–if you are using homemade dumpling wrappers (or 3/4 tbsp for store-bought dumpling wrappers)–of the filling to the middle. Then place about 1/2 tbsp of mozzarella cheese on top.
8. Begin wrapping the gyoza by pinching the center of the wrapper in half into a half-moon shape. Hold the gyoza in one hand and use the other hand to create pleats. Start on one side of the center pinch and make small pleats (about 2-4) towards the center, pinching each pleat firmly to seal. Repeat on the other side for a total of 4-8 pleats. Repeat with each gyoza wrapper. Follow the steps below for either the pan-frying method (which is most traditional), or baking method (for a more hands-off approach).

Pan-Frying Method:

To a well-oiled pan over low heat, line up your dumplings into a circular shape. Cook for about 8-10 minutes, or until cooked all the way through. Increase the heat and continue to cook (about 2 minutes) until the bottom of the gyoza is brown and crispy. Pour in about 1/2 cup of water and place a lid on top of the pan. Increase the heat to high and cook until the water is evaporated (about 3-5 minutes).

Baking Method:

To a well-oiled baking sheet, line up your dumplings in two rows, each about 1/2 inch away from each other. Place the baking sheet into your preheated oven and bake for 5-7 minutes.