Good Korean radishes are firm and the skin is a little shiny, without any scratches. The tops are pale green halfway down and fade to cream. It’s a varietal of the Daikon radish but it’s it’s shorter, fatter, and heavier, the flesh denser and the leaves a lot smoother. Peak season is late fall.
As soon as I bring a Korean radish home, I wrap it in a paper towel, put it in a plastic bag, and refrigerate it. This prevents it from drying out and becoming spongy. It will last for 2 weeks this way.
An example of good quality Korean radishes you should be choosing
Korean radish for sale in Noryangjin market, Seoul