In a small pot, over medium heat, heat the coconut milk along with the lemon grass and kaffir leaves and bring to just a boil. Remove from heat and let steep for 30 minutes, strain. Reheat liquid over medium-high heat, add the lemon juice and place the halibut in the middle of the liquid to poach. Cover with a parchment lid and poach in the oven until just beginning to flake. Remove from the oven and set aside.
In a large saute pan, over high heat, add the oil. When oil is hot, add the cabbage and saute until hot throughout. Add the vinegar, mirin and reduce. The cabbage will collapse and the liquid will evaporate. At this point add the sesame seeds and season with salt and pepper, to taste.
In a hot bowl add the cabbage first, top with the halibut and then the sauce.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.