Place veal between 2 sheets of wax paper; flatten veal to 1/4 inch pieces, using a meat mallet or rolling pin. Sprinkle veal with salt and pepper, and dredge in flour.
Combine the melted butter and olive oil in a large skillet. Cook the veal in the butter and oil until browned on both sides. Remove veal, reserving drippings in the skillet. Set aside, and keep warm.
Saute mushrooms and garlic in the drippings for 1 to 2 minutes. Return the veal to the skillet; add wine and lemon juice. Bring to a boil; cover, reduce heat, and simmer for 20 minutes. Add the capers and their liquid, and simmer for an additional minute.
Transfer the veal to a serving platter. Sprinkle with the parsley. Garnish with thin lemon slices.