Trim pork tenderloin of fat and sinewy tissue (silver skin). Cut in half cross-wise; cut each piece in half length-wise. Place pieces in Ziploc bag or on plastic wrap covered with another piece of plastic wrap. Pound to a thickness of ¼-inch. Set aside.
In a large bowl, whisk milk and egg together. Set aside.
Place flour, Kosher salt and pepper in a Ziploc bag. Shake to combine. Place Panko on a piece of waxed paper or plate.
Add pork to seasoned flour; shake to coat. Dip in milk/egg mixture and again coat in seasoned flour. Dip again in milk/egg mixture, and coat in Panko. Place in single layers on plate lined with waxed paper, with waxed paper between the layers; refrigerate for at least one hour.
Heat vegetable oil in a large skillet over medium heat. Add several pieces of breaded pork, and fry to a golden brown, 3 to 4 minutes per side; drain on paper towels. Repeat with remaining pork. Yield: 4 servings.