To make the salt water: In a bowl, mix the water and coarse sea salt. Whisk until dissolved.
To prepare the Napa cabbage: Cut the Napa cabbage in half, then cut it into quarters and remove the stem. Use the small leaves directly. Cut the big leaves lengthwise into about 1-inch pieces.
To soak the Napa cabbage: In a large mixing bowl, place the Napa cabbage inside and pour in the salt water. Rest until the Napa cabbage is slightly softened. Rinse the Napa cabbage under running water and drain well.
To make the sauce: In a mixing bowl, add the garlic, ginger, Korean red pepper flakes, fish sauce, Korean green plum extract, carrots, and scallions. Mix together.
To toss and serve: In a mixing bowl, place the Napa cabbage and the sauce mixture. Mix well. Lastly, sprinkle with the toasted sesame seeds. Enjoy.