Preparation: Wash zucchini and carrots. Slice spring onion into strips. Grate zucchini and carrots.
Batter Mixing: In a large bowl, mix flour, cornstarch, and baking powder. Add cold water to form a thin batter.
Cook the Vegetables: Heat cooking oil in a pan over medium-high heat. Add spring onions, zucchini, and carrots to the batter and mix well.
Cooking the Pajeon: Pour a thin layer of batter into the pan. Cook each side for 3-5 minutes, flipping gently with a spatula. Press down on the second side to ensure it stays thin (cooks faster).
Dipping Sauce: Mix dark soy sauce, white vinegar, sesame oil, and a sprinkle of white pepper in a small bowl. Enjoy the Yachaejeon with the dipping sauce!