Mix the ponzu and chili oil to make the dipping sauce.
In a bowl, toss the cabbage with the salt.
Transfer to a colander and let stand at room temperature for 15 minutes.
Wrap the cabbage in a clean kitchen towel and squeeze firmly to remove excess moisture.
In a large bowl, combine all filling ingredients and mix well.
Fold the gyoza: Hold a gyoza wrapper in your hand and place 1 tablespoon of the meat mixture in the center. Moisten the edge along the lower half of the wrapper, then fold the upper half over to meet it. Pleat one side into small folds, leaving the other side smooth. Press the edges firmly to seal. Repeat with the remaining wrappers.
Heat a skillet over medium-high heat and add the oil. Arrange the gyoza in the pan and cook until the bottoms are golden. Add about 60 ml of water and cover immediately with a lid.