Placing it in a bowl, I add a few spoonfuls of mayonnaise, not too much so it does not overwhelm the radish flavor. Then I add a pinch of sugar, a sprinkling of salt if necessary, and that is that. I have the radish base for a nice salad.
To top it all off, you can crumble a can of tuna on it, or canned crabmeat (real or imitation), sesame or other seeds. Chopped up scallions, chopped parsley, dill or aspoonful of grated carrots can add color to it.