DIRECTIONS:

1. Soak the sweetbreads in a large bowl of cold water for 3 hours, changing the water several times. Then remove the sweetbreads from the water and gently pull away as much of the outer membrane as you can, being careful not to tear the flesh. 

2. Fill a medium saucepan with 5 cups cold water, 1 teaspoon of coarse salt, and the white-wine vinegar. Place the sweetbreads in the pan and slowly bring the water to a simmer over moderate heat. Allow the water to simmer very gently for another 5 minutes.  Remove sweetbreads and place them in ice water for 10 minutes to stop the cooking.

3. Bring a large saucepan of water to a boil and cook haricots verts until they are crisp but slightly tender, about 5 minutes. Remove and reserve at room temperature.

4. In a small bowl combine the lemon juice with the balsamic vinegar and 1 tablespoon of the shallots. Slowly whisk in the hazelnut oil. Season to taste with salt and the additional black pepper. Reserve.

5. Place 2 tablespoons of the vegetable oil in a large skillet over moderately high heat. Add remaining shallots and sauté, stirring constantly, for 3 minutes. Add mushrooms, making sure the pan is not overcrowded. Sauté with a big pinch of salt, shaking pan occasionally, until mushrooms are nicely browned, about 5 to 7 minutes. Remove mushrooms from skillet and reserve.

6.  Combine the flour, the remaining 2 teaspoons of coarse salt, and the 1/2 teaspoon of black pepper on a plate and mix well. Add the remaining 3 tablespoons of vegetable oil to the skillet in which the mushrooms cooked, and place over high heat. Dredge sweetbread slices in the seasoned flour on both sides and add to hot oil. Sauté, turning, until sweetbreads are browned and crispy on the outside, about 3 minutes. Remove.

7. Toss reserved haricots verts and mushrooms together. Toss mixture with the hazelnut vinaigrette.  Garnish with chervil.