Radishes are good in soups, both
chilled and
hot.
Mhays, the radish and butter thing makes more sense when they are
mixed together. You can do something similar with cream cheese, which I prefer. Minced radishes and chives mixed with cream cheese are a good bagel schmear. Some people also like to mix chopped radishes and other veggies with cottage cheese.
This is a nice recipe:
Pea salad with radishes and feta.
Radish greens are OK when very finely chopped, but just OK.
Radishes can also be pickled. Here's an 18th-century recipe adapted from "Pleasures of Colonial Cooking."
Pickled radishes2 dozen radishes, greens removed
1 cup sugar
1 cup cider vinegar
1 tablespoon mustard seed
1/2 teaspoon celery seed
2 teaspoons dillweed
Cut the radishes into roses. Pack into a clean jar.
Combine the sugar, vinegar and seasonings in a saucepan over medium heat and simmer until the sugar is completely dissolved. Pour over the radishes.
Keep refrigerated. Give them a day or two absorb the flavors. (You can also can these in a boiling-water bath for 20 minutes, but with long-term storage the radishes soften and wrinkle.)
French breakfast radishes aren't shaped right for cutting into roses, but that step is optional.