Clean the scallions by washing them thoroughly, removing any dirt, and cutting off the root and any wilting leaves.
After washing, set them aside to drain. No need to completely dry but at least remove excess water.
Prepare the aromatics by blending together onion, radish, pear, and ginger. Set aside.
Prepare rice flour mixture by boiling water and rice flour together until it thickens. Once thick, allow it to cool before adding to the kimchi sauce.
Combine pepper powder, blended aromatics, fish sauce, soy sauce, corn syrup, sugar, plum syrup, sesame seeds, and rice flour mixture.
Mix the sauce thoroughly and give it a taste. It should be a little salty because it will even out later on once mixed with the scallions.
Lay the scallions on a flat baking sheet and spread the kimchi sauce through every stalk. Use your hands to get the sauce through every crease until everything is fully covered.
Place the green onions in a long rectangular container, laying them on top of each other carefully.
Ferment the green onion kimchi for a day at room temperature if you want it a bit sour, otherwise, fermenting it in the fridge for a day is okay too. This will last for 2-3 weeks and the flavor should continue to develop in that span of time.