In a bowl, combine the diced fresh and smoked salmon.
Place the bread and parsley leaves in a small food processor and pulse to make parsley bread crumbs.
Transfer bread crumbs to the salmon and lightly fold the breadcrumbs and lemon zest into the salmon to evenly distribute.
In a small bowl combine the mayonnaise, dijon mustard, capers, kosher salt and black pepper and stir well.
Add the mayonnaise mixture and lightly whisked egg to the salmon and fold in well to combine. Chill the salmon for 30 minutes to an hour before continuing.
FORM THE SALMON PATTIES:
Form the fish mixture into 6 equal patties and place them on a rimmed baking sheet. (Use my easy method for forming salmon patties so they won't fall apart). Refrigerate for half an hour so the patties have a chance to set.
Place panko in a shallow bowl and place a salmon cake on top. Sprinkle extra panko over the fish cakes, lightly pressing so the panko sticks to the salmon. Transfer to the baking sheet.
FRY THE SALMON CAKES
Place a skillet over medium heat to preheat the pan. (I used a cast iron skillet, but non-stick and regular fry pans work too.) Add a tablespoon of oil - oil should slick across the surface of the pan and moire.
Work with no more than 2 salmon cakes at a time. Fry on one side for 2-3 minutes.
Place one hand on top of the salmon cake and carefully edge a spatula under the cake. Gently turn the cakes over and continue to fry for an additional 2-3 minutes.
Set cakes on a tray lined with paper towels. Continue with the other cakes.
Serve salmon cakes with lemon wedges and tartar sauce if desired.