1.In a large bowl, combine the flour, potato starch, and salt. Add the kimchi, kimchi juice, 3 tablespoons water, and scallion. Use chopsticks to stir the mixture until well-combined.
2.Heat a cast iron pan over medium heat. Add 1 tablespoon vegetable oil and add all the batter to the pan, spreading it in an even thin layer. Fry until browned on one side.
3.Pick up the pancake and add another tablespoon of oil then flip the pancake on top and continue to cook until browned on the other side. Top with sesame seeds.
3.Meanwhile, combine the soy sauce, rice vinegar, sesame oil and 1 tablespoons water in a small bowl. Serve dipping sauce alongside the pancake. Serve immediately.