In a medium bowl, combine your tuna with mayonnaise, pepper, salt if needed, and pesto. Mix until well combined, then set aside.
For the bread, toast each side with butter under a broiler set to low, then add cheese onto the slices and broil once more for 3 minutes, or until cheese is melted and browned. Keep warm and set aside.
On a prepared board, place tuna in a medium bowl on the board.
Arrange the remaining ingredients around the center.
To make a sandwich, layer sprouts, tomato, pickles, avocado, chips, tuna, and another slice of cheesy bread.