Mix 2 tablespoons of soy sauce, 1 tablespoon of white vinegar, ½ teaspoon of gochugaru, 1 chopped scallion, and 1 teaspoon of toasted sesame seeds for the dipping sauce.
Mix ½ cup of all-purpose flour, 1 tablespoon of potato starch, and ¾ cup of water into a runny batter.
Measure 4 tablespoons of vegetable oil. Heat half in a large nonstick skillet over medium heat. Lay 12 scallions, trimmed to about 8in / 20cm, side by side in the pan.
Pour the batter evenly over the scallions. Scatter over 115g of chopped mixed seafood, such as shrimp, squid or clams, then drizzle with 1 beaten large egg and add 1 sliced red chili.
Cook for about 6 minutes, until the bottom is crisp, then flip and add the remaining oil around the edges. Cook for about 3 minutes, flip again and cook for 1 minute more. Serve with the dipping sauce.
