In a food processor, combine salmon, garlic, cilantro, soy sauce, mustard, and lime zest. Pulse to chop and combine until a coarse mixture is formed. Form 4 patties and place on a greased sheet pan. Cover with plastic wrap and refrigerate at least 1 hour, or overnight.

Cook burgers on a preheated grill for 12 to 15 minutes per side. Remove from grill and let rest for 5 minutes. Place each burger on a whole wheat bun with a few watercress leaves, 1 tablespoon Wasabi Mayo, and a few radish slices.