In large saucepan, combine radishes (I cut them in half), onions and chicken stock or broth.

Bring to a boil. Reduce heat and simmer 35 minutes. Remove from heat and cool slightly.

In food processor, puree mixture. Set aside.

In large saucepan or Dutch oven, melt butter. Whisk in flour and cook, stirring, 1 minute.

Add half and half and cook, stirring, until thickened, about 5 minutes.

Whisk in Worcestershire sauce, salt, pepper, horseradish and mayonnaise. Add pureed radishes.

Heat through. Can be held in slow cooker several hours if necessary.