Pre-heat the outdoor grill, if using, to medium-high and prepare the grill with cooking spray. Indoors, use a large skillet rather than a grill pan and pre-heat with a drizzle of EVOO to medium-high heat.
Place the salmon in a food processor and pulse to coarse grind the meat. Transfer the fish to a mixing bowl and season with the grill seasoning, poppy seeds, sesame seeds and dill. Mix and form four patties. Drizzle the burgers with EVOO.
Cook the burgers for 3 minutes on each side for a pink center, or 4-5 minutes on each side for fully cooked fish.
While the burgers cook, in a bowl, combine the cream cheese and the scallions, then fold in the sour cream and lemon juice.
Top the burgers with the lettuce, tomato, onion and sauce and serve on crusty, toasted buns.