Place turkey cutlets between two pieces of plastic wrap, and pound to about 1/4-inch thickness. Cut each into three or four pieces. In shallow bowl, combine flour, salt, and pepper. Dredge cutlets in flour mixture, coating well.
In large nonstick skillet, heat 2 teaspoons oil over medium-high heat. Add half of cutlets, and cook until browned, about 2 minutes. Turn cutlets and cook 1 minute longer. Transfer to platter; keep warm. Repeat with remaining oil and cutlets.
Increase heat to high, and add broth to skillet. Stir to loosen brown bits from bottom of skillet, then bring to a boil and cook until liquid is reduced to 1/2 cup, about 3 minutes. Dissolve cornstarch in 1 tablespoon water; whisk into reduced broth. Cook 1 minute more. Stir in lemon juice, butter, parsley, and capers, if desired. Spoon over warm cutlets.