If possible, buy undyed smoked fish for this as it has a more delicate flavour.
Using a sharp knife, cut up the fish roughly, then place the pieces in a food processor with the egg whites. Whizz until the mixture turns to a pasty consistency. Spoon this mixture into a separate bowl and mix in the spring onions with the breadcrumbs and cheese. Stir the mixture together thoroughly with a wooden spoon and season with the chilli powder and a little salt. Using damp hands, roll