Cut off the root of the scallion, then separate the white and leafy parts.
Take the white part, make an incision in the middle to spread it flat.
Once laid flat, roll it into a 3-inch length from top to bottom. Once rolled, thinly slice from right to left. Do the same thing to the leafy parts.
Afterwards, slice the onion thinly.
Fluff the scallions, combine them with the onion, and set aside.
In a bowl, combine soy sauce, pepper flakes, apple vinegar, sugar, sesame oil, Sprite, and sesame seeds.
When ready to consume, drizzle the sauce on top of the scallions, mix well, and enjoy with Korean BBQ!