Before you say ick!, now, I would never think of using radish tops.
But, why not? This soup is thick and rich and hearty and is a favorite at our CSA, Crazy Daisy Farm.
This is not an original recipe, however, the source is not known.
I did find reference to a discussion of Radish Top Soup from "The Origins of Fruits and Vegetables" by Jonathan Roberts and the same or a similar recipe on several other websites.
Radish Top Soup Total cook and prep time: 1 hour Ingredients

• 2 Tablespoons.
  butter
• 1 large onion, diced
• 2 medium potatoes, sliced
• 4 cups raw radish greens
• 4 cups chicken broth
• 1/2 cup heavy cream
• 5 radishes, sliced

Melt butter in a large saucepan over medium heat.
Stir in the onion and saute until tender.
Mix in the potatoes and radish greens.
Stir well to coat them with the butter.
Add the chicken broth.
Bring the mixture to a boil.
Reduce heat and simmer for 30 minutes.
Allow the soup to cool slightly.
Transfer to a blender and process until smooth.
You can also use a food processor or a hand immersion blender right in the saucepan.
As always, if using a non-stick saucepan, be careful with the immersion blender so you don't scratch the bottom of the pan.
If you used the blender of food processor, return the soup to the saucepan.
Stir in the heavy cream.
Cook and stir over low heat until well blended.
Do not allow to boil or become too hot or it could curdle the cream.
Serve with radish slices and a crusty bread.
If you don't make the bread yourself, look for local resources for artisan types of bread.
Many of the co-ops have in-house bakeries that produce incredible breads.
Tie into your local connections with fresh produce and bread.
Enjoy.