This recipe is from Food52.com (with only very slight modifications and notes). You can use any type of radish. Currently both the meat radish bulbs and greens are beautiful and are delicious in this soup. Great with crusty bread. If you prefer a totally smooth soup, just throw all ingredients together and cook until soft and then puree.
As soon as you get home, remove the leafy greens from your radishes. Wash them thoroughly and use them in this recipe well before they begin to turn ugly and useless. Saute the chopped onion and leek in butter.
Add the potatoes (peeled or not) and optional chopped anchovy. Cover with water (@1 inch above contents); add salt and pepper to taste. Bring to a simmer and cook until potatoes are completely soft (@30-35 minutes).
Add the fresh radish greens and chopped parsley. Simmer about 5 minutes. Let cool a bit and puree using an immersion blender or transfer to a blender/food processor.
Return to pot, if you have transferred to process. Bring back to a simmer. Finely chop about 1/2-3/4 cup of the fresh radishes and sprinkle with salt. Add these to the pot and cook until tender. Cut some additional raw radishes as rosettes and place in ice water in fridge for an optional garnish later if you like, either in the soup or alongside in a salad.
Stir the cream in to the pot, warm, but do not boil. Serve with an optional garnish of chopped parsley with a radish rosette, finishing salt and pepper to taste, and a toasted and buttered slice of artisan bread.