Fiddlehead soup

2 cups fiddleheads
1 medium onion, chopped
olive oil
fresh thyme, chopped
5-6 cups chicken broth
1/4 cup plain yogurt
horseradish, to taste
green onions, chopped

Cook onion in olive oil until soft. Add fiddleheads and thyme, saute for 5 minutes. Pour in chicken broth, bring to a boil and then reduce heat to simmer for 15-20 minutes. Puree soup in blender (work in batches) and return to pot. Stir in yogurt and heat through. Garnish with green onions.

Served with dark bread and thinly sliced roast beef.