If you are cooking pre-coated fish in the oven, pre heat the oven and follow the package instructions. If you'll be making the fish from scratch, heat up some vegetable oil in a heavy based casserole and refer to my "Crispy Batter Fried Fish" recipe, https://blogbystean.com/supper/crispy-batter-fried-fish/. You can do this in advance and quickly heat up the fish before assembling the tacos.
To make the salsa, add the juice and zest of two limes (or lemons) to a bowl. Finely chop up the chili and add to the lime juice. Dice up the mango into cubes of roughly 1 x 1 cm. Toss with the lime and chili and sprinkle in the roughly chopped coriander. Allow to cool in the fridge for 10-20 minutes.
To make the rainbow slaw mix, slice the cabbage into fine strips and julienne the carrots and beetroot (cut into long "matchsticks"). Roughly chop the spinach and coriander. Toss everything together.
To heat up the tortilla, place them one at a time onto an open gas flame burner, turning them constantly until lightly charred on both sides. This will take no more than 8-10 seconds. An electric stove top will also work - follow the same method.
To assemble the taco, dollop on some sour cream or spicy mayonnaise. Down the middle of the tortilla, place the fish goujons. Sprinkle over a handful of the rainbow slaw, followed by a couple spoonfuls of the mango salsa.
Fold the tortillas over and garnish with more fresh coriander and serve with an ice cold beer.