In a medium bowl, combine the diced mangoes, finely diced red onion, chopped fresh cilantro, and minced jalapeño if desired. Squeeze the juice of one lime over the mixture and sprinkle with a pinch of salt. Mix gently to combine and set aside.

In a large mixing bowl, whisk together the all-purpose flour, chili powder, cumin, garlic powder, onion powder, salt, and black pepper until well combined. Gradually pour in one cup of cold beer or sparkling water while whisking to create a smooth batter.

In a heavy pot, pour enough vegetable oil to fill it about 2 inches deep. Heat the oil over medium-high heat until it reaches 350°F (175°C).

Take your prepared fish fillets, cut into bite-sized chunks, and dip them into the batter ensuring they are fully coated. Fry for 3-4 minutes on each side until they are golden brown and crispy.

While the fish is frying, warm the corn tortillas in a skillet or over a flame until they are soft and pliable.

To assemble your tacos, take a warm tortilla, place a portion of crispy fried fish, and top with fresh mango salsa. Serve immediately.