Cut the salmon into 1-1/2-inch cubes. Place 2 or 3 of them in the work bowl of a food processor. Add the egg, garlic, shallot, lemon juice, parsley, 1/2 teaspoon salt and a few grinds of black pepper. Pulse until the salmon is pureed and the mixture is the consistency of a thick paste.
Add the remaining salmon along with the panko crumbs and pulse until the salmon is chopped into small chunks (about 1/2-inch). Do not over process. Transfer the mixture to a bowl.
Coat the inside of a 1/2-cup measure with nonstick spray and spoon a portion of the salmon mixture into it. Level it off and tap the mixture out onto a large plastic wrap-lined plate.
Repeat with the remaining salmon. You should get 4 patties. Using the back of a spatula, gently flatten each patty to a thickness of about 5/8-inch.
Cover loosely and place in the freezer for 15 minutes.
While the burgers chill, combine the mayonnaise, sun-dried tomatoes, lemon zest and chives in a small bowl and set aside.
Heat the olive oil in a nonstick skillet over medium-high heat. Carefully add the salmon burgers (they are rather delicate) and cook for 3 minutes.
Turn carefully and finish cooking for 2 to 3 minutes on the second side.
To serve, place some lettuce on the bottom of a hamburger bun, add a salmon burger and top with the sun-dried tomato and chive mayo.