1. Combine the veal, onions, carrots, lemon juice, and bouquet garni in a flameproof casserole and season with salt and pepper. Add enough water to cover. Bring to a boil over medium heat. Reduce the heat to low and simmer about 1 hour, or until the meat is tender.

2. Meanwhile, melt 2 tbsp of the butter in a frying pan over medium heat. Add the pearl onions and cook, stirring occasionally, about 5 minutes, until lightly browned. Add 2 tbsp of the remaining butter and the mushrooms. Cook, stirring occasionally, for 5 minutes, or until the mushrooms are tender.

3. Strain the stew, reserving 2¼ cups of the cooking liquid. Add the meat and vegetables to the mushroom mixture and cover.

4. Melt the remaining butter in a saucepan over medium-low heat. Whisk in the flour and cook for 1 minute. Whisk in the cooking liquid. Bring to a boil, whisking often.

5. Whisk the cream and egg yolks in a bowl, and gradually whisk in 1 cup of the sauce. Return to the saucepan. Pour the sauce over the meat and heat without boiling, stirring gently. Sprinkle with the parsley and serve hot.