1. In the bowl of a food processor, pulse salmon, panko, and egg white until salmon is finely chopped.
2. Form salmon into 4 (4-inch) patties; season with salt and pepper.
3. Heat grill to medium-high; cook, turning once, until burgers are just cooked through (5-7 minutes per side). Combine mayonnaise and soy sauce. Serve burgers with desired toppings and buns.