1. Put salmon, bread crumbs, egg, garlic, soy sauce, oil, scallions, and 2 tablespoons of the ginger in food processor. Pulse until coarsely chopped. Form into 4 equal (3" diameter) patties. Sprinkle tops with sesame seeds.
2.Heat large nonstick frying pan coated with cooking spray over medium heat. Put patties sesame-seed-side down in pan. Cook 5 minutes. Flip and cook until done, 5 minutes longer.
3.Serve burgers on buns and top with spinach and remaining 2 tablespoons pickled ginger.