Crack 1 egg into a bowl. Add kimchi brine, 1 T soy sauce, and ¼ cup water; whisk to combine. Whisk in the flour, then add kimchi and half of the scallions and stir to combine. Heat 1 T. oil in a skillet over medium-high. Drop ¼-cupfuls of batter onto opposite sides of skillet (you’ll probably only be able to cook 2 at a time). Cook pancakes until golden brown on the first side, 2–3 minutes, then flip and repeat on the other side. Transfer to a wire rack and let cool. Repeat the process in batches with remaining batter and oil; you should have 8 pancakes. Combine 3 T vinegar and remaining 3 T soy sauce in a small bowl. Transfer pancakes to a platter. Top with reserved scallions and serve with dipping sauce.