Cut the fish into chunks, then place them in a blender or food processor
Add the scallions, lemongrass, cilantro, curry paste, green chili, lime zest and juice to the fish. Season with salt. Process until finely ground.
Using lightly floured hands, divide the mixture into 16 pieces and shape each one into a small cake. Place the fish cakes on a plate, cover with plastic wrap and chill for about 2 hours, until firm.
Heat a wok over high heat until hot. Add the oil and swirl it around. Fry the fish cakes, a few at a time, for 6 to 8 minutes, turning them over carefully until evenly browned. Drain each batch on paper towels and keep hot while you are cooking the remainder. Serve on a bed of crisp lettuce leaves with shredded scallions, red chili slices, fresh cilantro sprigs and lime wedges