01 - Toss cabbage, red onion, cilantro, lime juice, and a pinch of salt in a bowl. Set aside to let flavors meld while preparing other components.
02 - Combine avocado, sour cream, cilantro, lime juice, garlic, salt, and pepper in a blender or food processor. Blend until completely smooth and creamy. Taste and adjust seasoning as desired.
03 - Whisk together flour, cornstarch, baking powder, salt, pepper, and paprika in a bowl. Gradually whisk in the cold sparkling water until a smooth, lump-free batter forms.
04 - Pour oil into a deep skillet or pot to reach 2-3 inches depth. Heat over medium-high heat until oil reaches 350°F. Maintain temperature throughout frying.
05 - Pat fish strips thoroughly dry with paper towels. Dip each strip into batter, allowing excess to drip off, then carefully place in hot oil. Fry in batches without overcrowding until golden brown and crispy, 3-4 minutes per batch. Transfer to paper towels to drain.
06 - Place portions of fried fish in each warmed tortilla. Top generously with slaw and drizzle with avocado crema. Garnish with additional cilantro if desired and serve immediately with lime wedges on the side.