1) To make the pistachio-mango pico de gallo salsa, mix all the ingredients in a bowl (chopped pistachios, mango, tomatoes and red onions), add some cilantro leaves and adjust salt and lime juice to taste.
2) In a separate bowl, add the shaved cabbage and mix with mayonnaise, white vinegar and sugar. Adjust salt to taste.
3) To make the batter, place the flour in a roomy bowl. Incorporate the beer until you have a smooth batter, add 2 tsp. Of Salt and set aside.
4) Heat the oil in a large pan over medium heat, dip a few pieces of fish into the batter, shake off the excess, then fry for about 4 minutes until crisp and golden. Repeat until you’ve cooked all fish, draining each batch briefly on a kitchen paper to remove excess oil. Sprinkle lightly with more salt.
5) Serve fish immediately in warm tortillas, over the shaved cabbage and the pistachio-mango pico de gallo salsa. You can garnish with more cilantro leaves and lime wedges!