Flatten the tenderloin pieces to make an inch thick medallion. Drizzle one side with lemon pepper.
In a heavy skillet, melt butter over moderate heat. Put the medallions and cook for about 4 minutes per side. Transfer pork to a serving platter, keeping them warm.
Mix lemon juice, Worcestershire sauce and mustard into pan juices in skillet. Stir while cooking. Pour over medallions and drible with chopped chives. Use whole chives as garnish and enjoy with veggies.