In the last fall I made an isolated storage box in our garage to store vegetables over winter. Although we are having freezing temperature in our garage over cold winter days my storage box was always above freezing point as its one side is our house wall. As I have not temperature control I found that it was even a little bit warmer that it should be for good vegetable storage. Here is the picture how our black radish looks on March 23.
We don't cook it. We simple grate it with other row root vegetables as red beet or carrots and dress with mayonnaises. Some time we cut it in small pieces and we eat straight with dipping in olive oil. As Passover is coming I guess that it would be a good option for something bitter for Passover eating.