Combine the canned salmon (with skin removed) and peeled baked or boiled potato in a mixing bowl, mashing until well blended.
Add 2 tablespoons soy sauce, 1 1/2 teaspoons freshly grated ginger, and 2 cloves crushed garlic to the salmon mixture. Stir to evenly distribute the seasonings.
Shape the mixture into 4 equal-sized patties and sprinkle 1/2 teaspoon cracked black pepper on one side of each patty.
Spray the patties lightly with olive or canola oil, then place them on a preheated grill. Cook for about 4 minutes on each side until crispy and golden, without pressing or flipping too soon.
While the patties are cooking, prepare the Asian sauce by mixing 1 tablespoon soy sauce with 2 tablespoons horseradish or wasabi.
Place cooked patties on whole-wheat buns, top with the Asian sauce, and add a handful of raw shredded cabbage. Serve immediately.