1. With knife held in slanting position, almost parallel to the cutting surface, cut tenderloin crosswise into 1/4-inch-thick slices. With meat mallet or dull edge of French knife, pound each slice to about 1/8-inch thickness. On waxed paper, mix flour, 1/4 teaspoon salt, and 1/8 tea spoon pepper. In pie plate, with fork, beat eggs and milk just until blended. Dip tenderloin pieces into flour mixture, then into egg mixture to coat.
2. In 12-inch skillet over medium heat, heat salad oil and 2 tablespoons butter or margarine (1/4 stick) until hot. Add tenderloin pieces, a few at a time and cook until lightly browned on both sides, removing pieces to warm platter as they brown and adding more butter or margarine if needed. Keep tenderloin pieces warm.
3. Into drippings in skillet, stir lemon juice and 4 tablespoons butter or margarine (1/2 stick); cook until butter is melted, stirring to loosen brown bits from bottom of skillet. Sprinkle tenderloin pieces with salt and pepper to taste. Pour butter sauce over tenderloin pieces; garnish with lemon slices and chopped parsley