In small bowl, stir together mayonnaise and Dijon until combined.
Spread mayonnaise mixture evenly over both slices of bread. Arrange turkey on one of the bread slices; top with cheese, tomatoes, pepper and lettuce. Place other bread slice on top and secure with four skewers or long toothpicks. Cut sandwich into four quarters diagonally.
Remember to include a cold source like a frozen juice box if you're packing this sandwich in a lunchbox.