Preheat the oven to 425°F (220°C). Line a baking sheet with foil and place the salmon fillet on it; drizzle with 1 tablespoon olive oil.
Roast the salmon for about 15 minutes, or until it flakes easily with a fork. Let the fish cool to room temperature.
Flake the cooled salmon into bite-sized pieces with a fork and transfer to a large bowl; drain any accumulated juices before continuing.
In a small bowl, whisk together 1/2 cup mayonnaise, 1 tablespoon Dijon mustard, 1 teaspoon Worcestershire sauce, the beaten egg, 1/8 teaspoon pepper, and 2 tablespoons chopped parsley.
Add the mayonnaise mixture to the flaked salmon and gently fold to combine, taking care not to overwork the fish.
Gently fold in 1/4 cup panko breadcrumbs until the mixture holds together.
Form the mixture into 6 even patties and place them on a parchment-lined baking sheet. Chill in the refrigerator for 15–20 minutes to firm up.
While the patties chill, make the lemon-dill sauce: in a small bowl combine 1 cup mayonnaise, lemon juice and zest from 1 lemon, 1 tablespoon whole grain mustard, 1/2 teaspoon salt, 1/2 teaspoon pepper, and 1/4 cup chopped dill; cover and refrigerate.
Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add the chilled salmon cakes and cook until golden on the first side, about 3–4 minutes.
Flip the cakes and cook until the second side is golden and the cakes are cooked through, about 3 minutes more (cook longer if frozen).
Transfer the cooked salmon cakes to a serving platter and serve immediately with the lemon-dill sauce.