Cut pork crosswise into 4 serving-size slices. Place between 2 pieces of plastic wrap. Working from the center, pound lightly with the flat side of a meat mallet to 1/4-inch thickness. Remove the plastic wrap.
In a shallow dish, combine flour, onion salt, garlic salt, and pepper. In a second shallow dish, stir together egg and milk. Place bread crumbs in a third dish. Dip each tenderloin slice into flour mixture; dip into egg mixture. Coat with bread crumbs.
Carefully drop one tenderloin at a time into deep hot oil (365 degree F). Fry for 1-1/2 to 2 minutes or until golden brown. Remove from the oil; drain on paper towels. (Place on a baking sheet in a 300 degree F oven to keep warm while frying the remaining tenderloins.)
Serve on warm buns. Pass the catsup, mustard, onion slices, and dill pickles. Makes 4 servings.