Begin by patting the white fish fillets dry to remove excess moisture. Season them with a pinch of salt and pepper.

In a mixing bowl, whisk together the all-purpose flour, cornstarch, paprika, cumin, cayenne pepper, salt, and pepper until well combined.

In a deep skillet, heat oil to 350°F (175°C) for frying. Test the temperature by dropping a small amount of batter into the oil; it should sizzle immediately.

Carefully coat each fish fillet in the batter, then fry until golden brown, about 3-4 minutes on each side. Once done, drain them on paper towels.

In a blender, combine ripe avocados, sour cream (or Greek yogurt), lime juice, cilantro, salt, and pepper. Blend until smooth.

Warm tortillas gently, then place a piece of fried fish on each. Drizzle generously with avocado crema and add toppings like cabbage or pico de gallo.