Make Batter (Time: 0-5 minutes): Whisk 1 cup all-purpose flour, 1 cup cold water, 1 egg, and pinch of salt until smooth. Let rest 5 minutes.
Prepare Vegetables (Time: 5-10 minutes): Cut 2 bunches scallions into 5-inch lengths. Cut 1 onion into thin slices. Slice 2 chili peppers.
Prepare Seafood (Time: 10-15 minutes): Clean 200g mixed seafood (shrimp, squid, clams). Pat dry thoroughly.
Make Dipping Sauce (Time: 15-17 minutes): Mix 2 tbsp soy sauce, 1 tbsp rice vinegar, 1 tsp sugar, 1 tsp sesame seeds, 1/2 tsp gochugaru (optional).
Cook Pancake (Time: 17-22 minutes):
Heat 10-inch non-stick or cast iron pan over medium-high.
Add 3 tbsp vegetable oil.
Arrange scallions in single layer.
Pour batter over scallions.
Arrange seafood and vegetables on top.
Cook 4-5 minutes until bottom is golden and crisp.
Flip and Cook (Time: 22-26 minutes):
Slide pancake onto plate.
Invert another plate on top, flip.
Slide back into pan with more oil if needed.
Cook 4-5 minutes until second side is crisp.
Serve (Time: 26-30 minutes):
Slide onto cutting board.
Cut into wedges.
Serve immediately with dipping sauce.
