Kkakdugi (radish kimchee)
As Hazzan observes, "kimchee alone comes in hundreds of varieties," from cucumber to scallion to eggplant, so it would be unreasonable to include all of them in this list. No one's got time for that much fermented product not called beer. But cubed radish kimchee with ground red chiles (gochugaru) is a crisp, slightly sweet, and plenty spicy staple among staples; it goes with the hearty beef soup called gumtang in particular.
Eomuk bokkeum (fried fishcake)
Bokkeum are essentially stir-fried dishes. Among banchan, the most common is probably fishcake. At its occasional worst, you may as well be chewing on Band-Aids; but at its best, the texture's almost pasta-like, the flavor rich and meaty beneath the sweet-savory glaze it attains during cooking.