1/4 cup unsalted butter
2 shallots, minced
1 onion, chopped
1 small russet potato, peeled and chopped
1 carrot, chopped
1 celery stalk, chopped
1 bay leaf
1 teaspoon fresh tarragon, chopped
2 Dungeness crabs, cooked, meat removed and shells reserved
2 cups
fish stock 2 cups cream
Salt and white pepper to taste
1 Tablespoon tarragon sprigs for garnish