Step 1Heat the oven to 300 degrees. Trim any fat or sinew from the rim of the cutlets. One at a time, flatten the cutlets: Place the meat between sheets of wax paper or inside a 1-gallon plastic bag; pound the cutlet with a meat pounder or a rolling pin to an even thickness of less than one-fourth inch. Repeat with remaining cutlets. Season lightly on both sides with salt.
Step 2Start the breading process: Place the flour on a plate, beat the eggs and milk until smooth in a wide bowl, and place the bread crumbs on a plate or in a wide bowl.
Step 3Dip a cutlet in the flour, lightly coating each side and shaking gently to remove any excess. Repeat with remaining cutlets. Dip a floured cutlet in the egg mixture and use your fingers to wipe away any excess. Place the cutlet in the bread crumbs and scoop more over the top, pressing firmly so the bread crumbs stick to both sides. Repeat with remaining cutlets. Set aside the cutlets on a plate or on a wire rack over a jellyroll pan for at least 15 minutes to allow the coating to set.
Step 4Heat the oil and butter in a wide skillet over medium-high heat until very hot. Test with a crumb of bread; it will sputter angrily when the oil is hot enough. Cook the cutlets until golden brown on one side, 2 to 3 minutes, then turn gently and brown on the other side, another 3 to 4 minutes. Don't crowd the pan; you will probably be able to cook only 2 cutlets at a time. As the cutlets are done, put them on a cookie sheet lined with paper towels, season lightly with salt, and place in the oven to keep hot.
Step 5Serve the cutlets immediately, with a piece of lemon to squeeze over.