In a medium bowl, combine diced ripe mangoes, finely chopped red onion, chopped fresh cilantro, and minced jalapeño pepper. Squeeze lime juice over the mixture and season with a pinch of salt. Toss gently until all ingredients are well-coated. Set aside.

In a large mixing bowl, whisk together all-purpose flour, chili powder, cumin, garlic powder, onion powder, salt, and black pepper. Gradually pour in cold beer or sparkling water, stirring until smooth.

In a deep pot, pour about 2 inches of vegetable oil and heat to 350°F (175°C). Use a thermometer to ensure accuracy.

Dip pieces of firm white fish fillets into the batter, ensuring fully coated, and fry for 3-4 minutes on each side until golden brown.

Heat a dry skillet over medium heat and warm corn tortillas for about 30 seconds on each side until pliable.

To assemble, take a warm tortilla, place fish in the center, and top with mango salsa. Serve immediately.