Classic Pork Gyoza From 'Japanese Soul Cooking'

Ingredients

• trimmed and finely chopped green cabbage
• teaspoon salt
• nira , bottom 2 inches trimmed to remove the hard stem, and finely chopped
• tablespoon finely chopped garlic
• tablespoon finely chopped ginger
• pound ground pork
• teaspoons soy sauce
• tablespoons toasted sesame oil
• teaspoon ground black pepper
• teaspoons sugar
• tablespoons katakuriko , plus extra for dusting
• round gyoza skins, 3 to 4 inches in diameter
• tablespoon katakuriko mixed with 3 tablespoons warm water
• Soy sauce
• Japanese rice vinegar
• Rayu
• water