Gently pound each veal piece between 2 sheets of plastic wrap to 1/8-inch thickness with flat side of a meat mallet or a rolling pin. Cover each veal piece with 1 piece prosciutto and 1 sage leaf; secure with wooden picks. Arrange veal on a large plate, prosciutto-side down; very lightly season with salt.

In a 12-inch heavy skillet, melt butter over medium-high heat until foamy; in 2 batches, cook veal, prosciutto-side down, 2 minutes, then turn and cook 10 seconds more. Reserving skillet with pan juices, transfer veal to a large serving platter. Add wine to pan juices and boil 30 seconds, then whisk in 1 tablespoon water. Pour juices over veal.