Cut the fish into 12 finger shapes and season lightly with salt, if you like.
Put the flour, egg and bread crumbs into three separate medium-sized sandwich bags or shallow bowls. First, coat the fish fingers, a few at a time, in flour, then egg and finally turn gently in the crumbs so they are evenly coated. (The fish fingers can be prepared to this stage and kept in the refrigerator for a day or frozen for up to 3 months.)
To cook, heat a frying pan over a medium heat and add the oil. If you plan on cooking just a few, use less oil. Once hot, add the fish fingers and cook for 2–3 minutes on each side until golden and cooked through. Alternatively, if you have the oven on, lightly toss the fish fingers in the oil, put on a hot baking sheet and cook for about 6 minutes until golden, turning halfway. (If cooking from frozen, add a couple of minutes on each side, and fry or bake until completely cooked through.)
Once the fish fingers are cooked, either warm your tortillas in the microwave or lightly toast under the grill/broiler, then tailor-make your tortillas to everyone’s liking. Serve hot.