To make the fish cakes, combine the smoked trout, potato, parsley, dill, lemon juice, lemon zest, olive oil, salt and pepper. Taste and adjust seasoning with salt, pepper and lemon juice, if needed.Divide the mixture into 8 and shape into patties.
Put the flour on a plate and season with extra salt and pepper. Lightly beat the egg in a small bowl. Put the breadcrumbs on a separate plate. Line them up on the kitchen counter, assembly line style. Dip a patty into the flour first, then the egg and then the breadcrumbs, ensuring it is well coated and re-shaping if necessary. Repeat with the remaining patties.
Heat the oil in a shallow frying pan over medium heat, and fry the patties in batches for a few minutes on each side or until golden brown. Remove and drain on a rack.
Serve warm or at room temperature with lemon wedges.
Makes 8 medium fish cakes.