1. Roughly chop the larger leaves of lettuce, leaving the smaller leaves whole. In a large bowl, combine the lettuce with the grated radishes and cilantro.
2. In a small bowl, combine the remaining ingredients, except the sesame seeds. (For a less spicy kimchi, use only 1/2w tablespoon of chile pepper flakes.) Whisk thoroughly to dissolve the sugar.
3. Pour the chile pepper mixture over the lettuce. Using tongs or wearing gloves, toss and coat the leaves evenly. Sprinkle on the sesame seeds and mix some more. Leave the kimchi to sit for 5 minutes and serve immediately.
Serves 4 as a side dish