In a large food processor, pulse salmon with red onion, jalapeno pepper (if using), lemon juice, panko, salt, and pepper until mostly chopped. Divide salmon mixture into 8 equal portions and form into patties. Refrigerate burgers for 30 minutes.
Heat grill to 450-500 degrees F. Spray grates with nonstick cooking spray or brush with oil. (Or line grates with a piece of oil-coated foil - see note below.)
Remove salmon burgers from refrigerator and place on grill. Cook 3 to 4 minutes on each side until cooked through. If you like your salmon more well done, cook 1 to 2 minutes longer.