Julienne the zucchini with a mandoline or knife, then toss with 3 pinches of salt to salt the zucchini. (While you prep the other ingredients)
Thinly slice the onion and add it to the zucchini.
Add the buchimgaru and 50ml of water, and mix gently and loosely with chopsticks.
Avoid a whisk or stirring too hard! Overmixing develops gluten in the flour, and it won't be crispy.
Heat a pan, add the olive oil, and pour in the entire batter at once, spreading it into an even layer.
Cook over medium-high heat as if frying. This is what gives a zucchini korean pancake its signature crisp edge. Flip and cook both sides until crispy and golden.
If the pancake absorbs all the oil as it cooks, add more oil 2 tablespoons at a time so the bottom keeps frying, that's what makes it crispy.
Make the Korean pancake sauce. While the pancake cooks, mix together the soy sauce, mirin, gochugaru, and sesame seeds.This soy sauce is delicious with other Korean pancakes too!