Step 1Combine the mayonnaise, wasabi paste and honey in a small bowl. Taste; adjust the wasabi. (This can be made a few days ahead and refrigerated.) Makes a little more than 1/2 cup.
Step 1Finely mince together the garlic, onion, pickled ginger, wasabi paste, sesame oil, sugar, oyster sauce, salt and pepper in a mini-processor. Add the egg white. Pulse just until the egg white is mixed in.
Step 2Combine the salmon and the garlic mixture and mix them together with a fork until they're well combined. Divide the mixture into 4 equal portions, then shape each into a patty, about 1/3-inch thick. Wrap each separately in plastic. Chill the patties at least 2 hours.
Step 3Just before serving, heat the butter or oil in a large nonstick skillet over medium heat. When hot, cook the patties until they're lightly browned on each side, about 4 to 5 minutes total. They should be slightly pink in the center.
Step 4Meanwhile, lightly spray the cut sides of the buns with the nonstick spray. Place the buns, cut side down, on a hot griddle to toast, about 1 minute.
Step 5To serve, spread about 1/2 tablespoon of the Wasabi Sauce on each toasted bun. Place the patties on 4 halves. Top them with some pickled ginger and close the bun. Serve the burgers immediately, passing extra sauce and ginger.