Remove the wire rack from your oven. Heat your oven to 200°C/Fan 180°C/Gas 6. Lay each tortilla over 2 bars of the wire rack. Most of the wrap should hang down through the bars to make scoops. This will give you crisp tortilla taco shells. Slide the shelf in the oven and bake for 5 mins till golden and crisp.
While the tacos bake, peel and finely slice the red onion. Squeeze the juice from the orange into a bowl. Stir in a pinch of salt. Add the onion and stir to mix. Set aside.
Tip the fish pie mix into a bowl. Sprinkle in 2 tsp Cajun spice mix and add a pinch of salt. Gently stir to coat the fish in the spice mix. Set aside.
Halve the avocado, scoop out the stone and then scoop out the flesh. Pop it in a bowl and roughly mash the avocado with the back of a fork. Finely grate the lime zest over the top, then squeeze over the juice. Halve the chilli, scoop out the seeds and white pith and finely chop it. Stir the chilli into the limey mashed avocado.
Halve the cherry tomatoes and add them to the bowl. Finely slice the lettuce leaves and add them to the tomatoes. Tip in the red onions with their juices. Add 1 tbsp oil and a pinch of salt and pepper. Toss to mix.
Put a frying pan on a medium heat for 2 mins to warm up. Add 1 tbsp olive oil and the fish pie mix. Fry for 5-6 mins, stirring now and then, till the fish is cooked through – it will look opaque and flake easily when pressed with a fork. Scoop the fish pie mix into a bowl.
Fill the taco shells with a little salad, Cajun fish and the smashed avocado. Serve the extra salad and smashed avocado on the side.