In a mixing bowl, combine the fresh fish fillets, mashed potatoes, beaten egg, parsley, green onions, lemon juice, salt, and black pepper. Mix until well combined.

Form the mixture into patties, about 2-3 inches in diameter.

Coat each patty in bread crumbs, pressing gently to adhere.

Heat vegetable oil in a frying pan over medium heat.

Add the fish cakes to the pan, cooking in batches if necessary, and fry for about 4-5 minutes on each side or until golden brown.

Remove from the pan and drain on paper towels.