1 medium onion, chopped
2 tablespoons (30 mL) butter or oil
4 cups (1 L) chicken stock
1½ cups (375 mL) peeled, diced potatoes
2 cups (500 mL) cleaned fiddleheads
1 bay leaf
Salt and pepper to taste
1½ cups (375 mL) milk
Garnish: yogurt, grated lemon rind, or chives
In a large, heavy-bottomed saucepan, sauté onion in butter or oil until soft but not brown, about 5 minutes. Add potatoes, fiddleheads, bay leaf, and enough chicken stock to make the vegetables just swim.
Bring to a boil, reduce heat and barely simmer, partially covered, for one hour. Remove from heat and cool slightly. Remove bay leaf.
In a blender, process mixture in batches. (Can be prepared to this point a day or two ahead. Cool, cover, and refrigerate.)
Return mixture to saucepan and slowly bring to a simmer, stirring frequently. Add milk, a little at a time, until it reaches the consistency you like. Add salt and pepper to taste. Serve in heated soup bowls, garnished as desired.