Sprinkle seasoning on shrimp and set aside. Mix together egg and milk. Dip shrimp into egg and milk mixture and then dredge in flour. Shake off excess flour. Heat butter in a sauté pan over medium heat. . Sauté shrimp in butter for 2 minutes on each side. Place mustard into pan and toss butter, shrimp, and mustard together. Sauté until the shrimp is well coated, shaking pan to prevent burning.