1) Heat 2 cm of oil in a large skillet over medium heat. While oil is heating, combine tuna, beaten egg, spring onions, mayonnaise, breadcrumbs and lemon juice, to taste (if desired). Form into patties and dust with additional breadcrumbs.
2) When oil is hot, fry patties until golden brown, about 2 minutes on each side. Remove from oil and drain on paper towels before serving.