Chill fish in freezer until firm.
Chill grinder blade for 15 minutes.
Assemble grinder attachment and set a large bowl next to it to catch the ground flesh.
Grind the marlin. If you don't have a grinder, you can pulse the flesh in a food processor, being careful to not let the flesh go mushy.
Combine marlin, bread crumbs, egg, onion, ginger, and garlic in a large bowl.
Add mayonnaise, olive, grapeseed or canola oil, and toasted sesame oil.
Form into small patties. Season with salt and freshly ground black pepper.
Grill or pan-fry burgers over medium heat until just cooked through, 3-4 minutes per side.