In a large mixing bowl, combine well-drained canned tuna, chopped onion, grated carrot, and green onion. Season generously with salt and pepper, then crack in the eggs and sprinkle in the flour. Mix everything together gently until just combined.

Using your hands, shape the mixture into small patties about 2-3 inches in diameter, yielding around 8 fish cakes.

Heat a non-stick skillet over medium heat and add vegetable or canola oil to coat the bottom. Once hot, carefully lay the patties in a single layer, cooking for 2-3 minutes on each side until golden brown.

While the patties are frying, combine mayonnaise, gochujang, lemon juice, and sugar in a small bowl. Mix until smooth.

Transfer cooked tuna cakes to a paper towel-lined plate. Serve warm, garnished with fresh herbs if desired, with spicy mayo on the side.