Make the jalapeño mayonnaise by combining 1/2 cup mayonnaise, the minced garlic clove, 2 tablespoons diced pickled jalapeños, and 1 tablespoon jalapeño pickle juice; mix well and refrigerate until ready to serve.
Drain and flake the 15 ounces of pouched or canned salmon into a medium bowl, removing any large bones as needed.
Add 1/2 cup Panko, 1 large egg, 1/4 cup mayonnaise, 2 teaspoons Cajun seasoning, 1/2 finely diced red bell pepper, 1/3 cup finely diced onion, 1/2 teaspoon garlic powder, and 1/2 teaspoon black pepper to the salmon; stir until evenly combined.
Form the mixture into 6 to 8 even patties, then place them on a tray and freeze or refrigerate for 20 minutes to firm up.
Heat 1 to 2 tablespoons vegetable oil in a large nonstick skillet over medium heat.
Cook the patties in the hot skillet for about 3 minutes per side, or until golden brown and heated through; work in batches if needed so they don't crowd the pan.
Serve the salmon cakes hot with the chilled jalapeño mayonnaise.