In a large bowl, combine the flour, salt, and baking powder. Add the beer and whisk until smooth. Let sit for 15 minutes.
Heat the vegetable oil in a large pot until it reaches 180°C.
Coat the fish in the batter, then transfer to the oil and fry until golden on the outside and cooked through, 5-7 minutes. Drain the fish on a wire rack set over a baking sheet lined with paper towels
Serve crispy fish on warm tortilla, top with fresh red cabbage, coriander and a drizzle of BLACK MAMBA JALAPEÑO CHILLI SAUCE, dollop of sour cream and garnish with lime wedge.