Make the Chipotle Crema: In a small bowl, whisk together the mayonnaise, chopped chipotle peppers in adobo, lime juice, minced garlic, and a pinch of salt. Taste and add more chipotle sauce if you'd like more heat. Cover and place in the fridge until ready to serve.

Prepare the Slaw: In a medium bowl, combine the shredded red cabbage, grated carrot, and chopped coriander. In a separate small bowl, whisk together the lime juice, olive oil, sugar, and salt. Pour the dressing over the cabbage mixture and toss well to combine. Let it sit for at least 15 minutes to soften slightly.

Heat the Frying Oil: Pour the vegetable oil into a large, deep saucepan or Dutch oven until it's about 5cm deep. Heat over medium-high heat until it reaches 180°C (350°F) on a cooking thermometer. If you don't have a thermometer, a small drop of batter should sizzle immediately and turn golden in about 30 seconds.

Mix the Batter: While the oil is heating, prepare the fish batter. In a large mixing bowl, whisk together the plain flour, cornflour, baking powder, smoked paprika, garlic powder, salt, and pepper. Just before you're ready to fry, pour in the very cold sparkling water and whisk gently until just combined. A few lumps are perfectly fine – do not overmix! I find that a light, quick whisk is all it needs.

Batter and Fry the Fish: Pat your cod strips completely dry with kitchen paper one last time. Working in batches to avoid overcrowding the pan, dip each piece of fish into the batter, letting any excess drip off. Carefully lower the battered fish into the hot oil.

Cook Until Golden: Fry for 4-5 minutes, turning occasionally, until the batter is a deep golden brown and exceptionally crispy. Use a slotted spoon to remove the fish and place it on a wire rack set over a baking sheet to drain. This keeps the underside crispy. Sprinkle lightly with a little extra salt while hot. Repeat with the remaining fish.

Warm the Tortillas: You can warm the tortillas by heating them for 20-30 seconds per side in a dry, hot frying pan until they are soft and lightly toasted. Alternatively, wrap the stack in foil and warm in a 150°C (130°C fan) oven for 10 minutes.

Assemble Your Tacos: To build your Baja fish tacos, place a piece or two of crispy fish onto a warm tortilla. Top with a generous spoonful of the slaw, a drizzle of the chipotle crema, and a few slices of avocado if using. Serve immediately with extra lime wedges on the side.