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 batter forms. The consistency should be thick enough to coat the fish but still pourable.
04 - Pour oil into a deep skillet or pot to a depth of about 2 inches. Heat over medium-high heat until it reaches 350°F. The oil is ready when a small drip of batter sizzles immediately upon contact.
05 - Pat fish strips completely dry with paper towels. Dip each strip into the batter, allowing excess to drip off, then carefully place in the hot oil. Fry in batches without overcrowding for 3-4 minutes until golden brown and crispy. Transfer to paper towels to drain.
06 - Place a portion of fried fish in each warm tortilla. Top generously with the prepared slaw and drizzle with avocado crema. Garnish with additional cilantro if desired and serve immediately with lime wedges on the side.