Add salt to the water and mix until it has dissolved.
Sift the flour into a large bowl.
Add water to the flour and mix with a rubber spatula. If necessary, add a tablespoon of water.
Transfer the dough to the work surface and knead the dough for 10 minutes. After 10 minutes the dough will be much softer. When it is done, cut it in two.
Shape each half into a long log, about 3 cm in diameter. Wrap each log with plastic wrap. Let it sit for 30 minutes.
After the dough has rested, cut each log into 20 pieces and cover with a damp cloth. Roll out each piece so you can cut out a circle with an 8 cm cookie cutter. If the dough rolls back, wait a few seconds, then cut out the circle. Sprinkle with some starch to prevent the wrappers from sticking. Save the scraps under the damp cloth and use them to make more wrappers.
Heat up a skillet and add 1 TBSP cooking oil. Saute the onion until golden, then add garlic, ginger and the white part of the spring onion. Saute for a minute or two. Remove from the pan and let cool for a few minutes.
Add this mixture to ground meat, chopped green parts of the spring onion, cilantro and soy sauce. Mix to combine.
Run a wet finger around the edge of the gyoza wrappers. Place a teaspoon of filling in the center and Fold the wrapper in half and seal the edges by pressing with fingers. This will create a simple dumpling. If you want the edges to look more artistic, there are a lot of good youtube videos to show you how to do it.
Place dumplings in a heated skillet with 1 TBSP cooking oil. Fry for 2-3 minutes or until you get the nice deep brown sear on the bottom.
Add 1/3 cup water per 6 dumplings and cover. Cook for 7-8 minutes. If the water runs out, you can add more one TBSP at a time.
Combine all ingredients to make the dipping sauce.
Sprinkle the dumplings with chopped cilantro, spring onion greens, and sesame seeds. Serve with the dipping sauce.