1tablespoonwateror maesilcheong, Korean plum extract
Cut the beef into thin strips (about 3-inch long). Remove the stems off the soaked mushrooms. If the mushrooms are thick, place the stem side down, and carefully slice parallel to the cutting board. Then cut into thin strips.
Season the beef and mushrooms with the seasoning ingredients.
Cut the cucumbers crosswise into 2-½ inch long sections. Cut each one into thin sheets discarding the seedy part, and then cut into matchsticks.
Cut the zucchini crosswise into 2-½ inch long sections. Cut each one into thin sheets, discarding the soft, seedy part, and then cut into matchsticks.
Cut the carrot into matchsticks.
Bring a small pot of water to a boil. To keep the shrimp straight after cooked, insert a toothpick straight through the leg part of each shrimp. Cook briefly, about a minute. Quickly drain and dump in cold water to stop cooking. Drain again. Remove the toothpicks. Cut into thin strips.
Add the flour and salt to a bowl. Stir in 1-1/3 cups of cold water, and mix well. The batter should be thin.
Separate the eggs. Lightly beat the white by gently cutting it with a spoon. Stir the yoke with a spoon until smooth. Heat a lightly oiled nonstick skillet over medium low heat. Pour each egg part into a thin layer, spreading with a spoon. Cook each side briefly. Do not brown the egg. Cool then first cut into 2-½ inch wide sheets, and then into thin strips.
Heat the pan over medium high, add a half tablespoon of oil, and briefly cook each ingredient, sprinkling with a pinch of salt, in this order: cucumber, zucchini, carrot, mushroom, and beef,. Transfer to a large plate.
Heat a lightly oiled non-stick pan over medium low heat. Add one tablespoon of the pancake mixture into the pan, and spread it evenly into a thin round shape (about 3 inch round) with a back of the spoon. Cook until the edges start to lift up slightly, about 30 seconds, and flip over for another 30 seconds. Transfer to a large plate. Repeat until all the mixture is used.
Arrange the filling ingredients, placing the same/similar color foods on opposite sides. Stack the pancakes up and place in the center section of the platter.
In a small bowl, mix the hot mustard paste and sugar until the sugar is dissolved. Add the remaining liquid ingredients and mix well again. Serve with the gujeolpan.