- 6 tablespoons butter
- 1 Leek, white part only, well rinsed, thinly sliced
- 1 yellow Onion, chopped
- 1 Carrot, peeled and sliced
- 1 Shallot, minced
- 6 tablespoons flour
- 4 cups chicken stock, heated
- 1 1/2 cups milk, scalded
- Bouquet garni (2 Parsley sprigs, 3 bay leaves and 1 sprig fresh Thyme)
- 1/2 cup heavy cream
- 2 egg yolks
- 1 cup chicken stock, heated
- 4 tablespoons Dutch Mustard with whole mustard seeds (De Echte Zaanse Mosterd)
- 1/2 teaspoon white pepper
- 1 teaspoon salt
- 1 tablespoon snipped, fresh Chives
- 1/2 cup crème fraîche
- Optional: 1/2 pound green Asparagus, lightly steamed, cut into 1" pieces and 1/3 pound Black Forest ham, sliced and cut into little pieces
Place the butter in a stock pot over medium heat. When melted, add the Leek, Onion, Carrot and Shallot. Sauté until the vegetables are soft, about 5 minutes. Add the flour and cook for 5 minutes while stirring to remove the taste of the flour.
Gradually stir in the hot chicken stock and hot milk. Add the bouquet garni, reduce the heat to low and simmer uncovered for about 45 minutes, stirring frequently. Strain the thickened soup into a clean soup pot, pressing the solids to extract as much liquid as possible. Add the cream and bring back to a simmer. Reduce the heat to low.
Whisk the egg yolks in a medium bowl. While whisking, slowly incorporate a 1/4 cup of hot soup into the egg yolks. Incorporate another 1/2 cup of hot soup into the egg yolk mixture, whisking steadily. Then, incorporate a full cup of hot soup into the egg yolk mixture, whisking steadily. Return the egg yolk and soup mixture into the soup pot, whisking to blend. Thin the soup with the additional cup of heated chicken stock (more or less) to reach the desired thickness.
Over medium heat, bring the soup to just simmering. Whisk in the Mustard, salt and pepper to taste. Add the crème fraîche, whisking until smooth. Optional: Add the drained, cut Asparagus and pieces of ham. Serve piping hot, topped with chopped chives.