1 Finely dice tuna and in a large bowl mix with capers, red onion, mustard, lemon juice, salt, and pepper.2 Moisten hands and shape tuna mixture into eight 4-ounce burgers (about the size of the palm of your hand and thickness of a deck of cards). Place prepared burgers on a plate, cover, and refrigerate at least 1 hour (or freeze for about 5 to 10 minutes).3 Spray grill or grill pan with nonstick cooking spray and heat to medium-high. Grill burgers about 2 minutes per side (or longer if you like them more well-done).4 Place burgers on bottoms of buns or sandwich thins and top each burger with one slice of tomato, three slices of avocado, and bun/thin top. Serve and enjoy!
