In a medium pot, combine 4 cups of dashi, 1/4 cup of sake, 3 tablespoons of soy sauce, and a pinch of salt. Bring to a gentle boil over medium-high heat.

Reduce heat to a simmer and add 2 cups of chopped napa cabbage, white parts of 3 scallions, and 1 cup of sliced shiitake mushrooms. Simmer for 10 to 12 minutes until cabbage is tender.

In a separate pot, bring water to a rolling boil and cook gyoza for about 1 minute or until they float to the surface. Transfer to the simmering broth.

Let gyoza simmer in broth for an additional 2 to 3 minutes.

Stir in green parts of the scallions and drizzle in 1 tablespoon of toasted sesame oil before serving in bowls.