Pound veal scallops with a mallet until thin and even in thickness.
Brush both sides lightly with a mixture of water and brown bouquet sauce.
Cook a few pieces of veal in hot butter in a skillet just until done (about 1 minute on each side).
Sprinkle lightly with salt.
Keep warm in oven while cooking remaining veal.
While veal is cooking, mix wine, stock, onion, and garlic in a small saucepan.
Simmer until onion is tender (about 3 minutes).
Stir in lemon juice, pepper, and salt.
Mix arrowroot with a little cold water.
Stir into simmering stock mixture.
Simmer, stirring constantly, until mixture thickens.
Arrange veal on warm plates.
Pour sauce over.
Sprinkle with parsley.