Place a large skillet over medium-high heat.
Add a drizzle of oil and cook the fish, sprinkling with salt and pepper, for 3-4 minutes per side, or until just cooked through. Set aside and flake into pieces with a fork.
In a saucepan, cover the potatoes with water, bring to a boil and simmer for 15 minutes, or until tender.
Drain and transfer to a large bowl and mash with a potato masher or fork.
Add the egg, green onions, cod and some salt and pepper to taste. Mash with a fork and stir to combine everything well.
Shape the mixture into patties any size you like and dredge in breadcrumbs to coat.
Heat a drizzle of oil in the skillet over medium-high heat and cook the patties in batches until they are golden and crisp; 4-5 minutes per side.