How to Make It
In a large bowl, combine the napa cabbage and bok choy. In a large saucepan, combine the salt and 1/4 cup of the sugar with 2 quarts of water and warm over moderate heat just until the salt dissolves. Pour the brine over the cabbages and let stand at room temperature for 30 minutes.
Rinse and drain the cabbages. Transfer to a large bowl and add the garlic, ginger, red pepper flakes, fish sauce, sesame oil and the remaining 1 teaspoon of sugar; toss well. Let stand for 30 minutes. Garnish the kimchi with sesame seeds before serving.