Combine the tuna, shallot, eggs, panko, and parsley in a large bowl. Season with salt and pepper. Add some extra panko if the mixture is too wet. Shape the mixture into two burgers with your hands. Cover and chill in the fridge for 20 to 30 minutes to allow the burgers to firm up.
Mix the mayonnaise with the lemon zest and half of the juice in a bowl and set