Make salsa by combining its ingredients in a bowl. Cover and refrigerate until needed.
Preheat your barbecue or indoor grill to medium-high. Brush the salmon with the 1 1/2 Tbsp. olive oil, and then sprinkle with the Cajun spice. Lightly oil the surface of your grill. Grill the salmon 3 to 4 minutes per side, or until just cooked through.
Spread each bottom bun with mayonnaise and then top with lettuce. Set a piece of salmon on each bottom bun. (If desired, carefully pull off the skin from each salmon fillet before doing so). Top the salmon on each bun with a generous spoon of the salsa, set on top buns and serve.
Note: Cajun spice is sold in our bottled herb and spice aisle.
Options: Instead of salmon, grill and sandwiched another type of fish fillet in these burgers, such as halibut.