In a large mixing bowl, combine all-purpose flour, rice flour, cornstarch, salt, and optional sugar. Gradually whisk in ice-cold water until smooth. Cover and refrigerate for at least 30 minutes.

While the batter rests, finely chop the Korean spring onions, carrots, and onion. Mix with optional seafood, kimchi, and chilies.

In a small bowl, whisk together soy sauce, rice vinegar, and sesame oil. Optionally mix in gochugaru and minced garlic. Sprinkle sesame seeds on top.

Heat 2 tablespoons of vegetable oil in a non-stick skillet over medium-high heat. Pour half of the batter, spread evenly, and scatter half of the filling on top, pressing gently.

Cook the pancake for 5–7 minutes until edges are golden and crispy. Lift with a spatula to check readiness.

Carefully flip the pancake and cook for another 5–7 minutes until golden and crisp on the other side.

Remove the first pancake, keep warm, and repeat with remaining batter and filling.

Once all pancakes are cooked, cut into wedges and serve hot with dipping sauce.