FOR THE SWEET PICKLE RELISH
WHISK together all the sauce ingredients for sweet pickle relish, then set aside.
MAKE the salmon burgers: In a food processor, pulse the salmon until finely minced, then transfer to a large bowl. Add 1 cup of the panko, the mayonnaise, parsley, dill, capers, salt, Worcestershire, lemon zest, pepper and garlic. Using your hands, mix until incorporated, then form into six 4-ounce patties. Coat the patties in the remaining 1 cup of panko bread crumbs.
HEAT 2 tablespoons of vegetable oil, in 2 large nonstick skillets, over medium-high heat. Add 3 burgers to each pan and cook, flipping once, until golden brown and cooked through, 4 to 5 minutes.
SPREAD the relish on the bottom halves of the buns then place a fish burger on each. Top with more relish, shredded iceberg lettuce and the remaining bun halves, then serve.