Heat the oil in a large pan over medium heat. Add the gyoza and fry until they are brown and crispy on the bottom.

Add in the water and quickly cover the pan with its lid. Reduce the heat to low and allow the gyoza to steam until thawed and hot through. Remove the lid and allow the excess water to evaporate and the bottoms to crisp up again.

Rinse the bok choy well under running water to remove any dirt. In a small pot, bring the stock to a boil. Add the mushrooms and stand the bok choy up so that only the stems are submerged. Reduce the heat to a simmer and allow the bok choy to cook for 3 - 4 minutes until the stems are tender.

Add the noodles and lay the bok choy down to cook the leaves. Cook the noodles for the length of time indicated on the package (for fresh udon, about 2 ½ minutes).

In one of your serving bowls, combine the cashew butter, soy sauce, vinegar, and sesame oil. Mix well until a thick paste is formed. Remove half the paste to your second serving bowl.

Add one ladle of hot soup stock to each bowl and mix well to dissolve the cashew butter mixture. Divide the noodles between each bowl and add the remaining stock. Top with mushrooms and bok choy.

Spoon over some chili crisp and serve.