Pat fish strips dry and season lightly with salt and pepper.
In a bowl, whisk flour, baking powder, paprika, garlic powder, salt, and pepper.
Gradually whisk in cold beer or sparkling water until a smooth batter forms.
Heat 1–2 inches of vegetable oil in a deep skillet to about 350°F (175°C).
Dust fish lightly with flour to help batter stick.
Dip each fish strip into batter, letting excess drip off.
Fry fish in batches, 3–4 minutes per side, until golden and crisp; transfer to a wire rack to drain.
Mix shredded cabbage with a squeeze of lime and a pinch of salt for quick slaw.
Whisk together sour cream, mayonnaise, lime juice, honey, salt, and pepper to make crema.
Warm tortillas in a dry skillet or wrapped in foil.
Assemble tacos: tortilla, slaw, crispy fish, avocado slices, crema, cilantro, and hot sauce if desired.