Mix the dipping sauce: In a small bowl, stir together soy sauce, rice vinegar, sesame oil, sugar, and optional garlic and chili. Set aside so the flavors meld.

Prep the vegetables: Cut scallions into 2-inch pieces. If using add-ins like zucchini or shrimp, make sure they’re dry to prevent sogginess.

Make the batter: In a bowl, whisk flour, cornstarch, salt, and pepper. Add the egg and cold water. Stir until just combined. The batter should be pourable—like thin pancake batter. If it’s too thick, add a tablespoon of water at a time.

Fold in fillings: Add scallions and any optional vegetables or seafood to the batter. Stir gently to coat without overmixing.

Heat the pan: Place a large nonstick or well-seasoned skillet over medium-high heat. Add a generous swirl of oil—enough to lightly coat the surface.

Cook the first side: Pour in about half the batter and spread it into a thin, even layer. Don’t pack it down too firmly; you want some texture. Cook 3–4 minutes until the bottom is golden and crisp around the edges.

Flip carefully: Slide a spatula under the pancake and flip in one motion. If it feels fragile, cut the pancake in half in the pan and flip in two sections. Cook another 2–3 minutes until the second side is browned and crisp.

Repeat: Add a bit more oil and cook the remaining batter the same way.

Serve hot: Cut into wedges, sprinkle with sesame seeds and extra scallions if you like, and serve with the dipping sauce.