1. Soak the seaweed in water for about 30 minutes.
2. Heat 2T sesame oil and 1t minced garlic in a pot, add the soaked seaweed and blanch briefly, then add 500ml water, 1t seasoned salt, and 1t oyster sauce, and simmer.
3. While the seaweed soup cools slightly, salt the flounder, let sit about 10 minutes, pat dry, and pan-sear in olive oil on both sides.
4. Blend the seaweed soup from step 2 until smooth, pour back into the pot, add 1t butter and 2T heavy cream, and simmer a little longer.
5. Pour the seaweed cream soup from step 4 into a bowl, and top with the flounder steak from step 3 and chopped perilla leaf.