Combine sour cream, mayonnaise, lime juice, garlic powder, and salt in a small bowl. Whisk until smooth and refrigerate.
Whisk lime juice, olive oil, honey, salt, and pepper in a small bowl. Toss with shredded cabbage and set aside.
Pat fish fillets completely dry with paper towels and cut into 3-4 inch strips.
Whisk together flour, baking powder, garlic powder, smoked paprika, cumin, salt, pepper, and cayenne. Slowly add cold beer or sparkling water and whisk until smooth.
Heat vegetable oil in a cast iron skillet to 350°F (175°C).
Dredge fish strips in plain flour, dip in batter, and fry in small batches for 3-4 minutes until golden brown, turning once. Drain on a wire rack.
Warm tortillas in a dry skillet over medium-high heat for 20-30 seconds per side or in the microwave wrapped in a damp towel.
Place fried fish on warm tortillas, top with slaw, drizzle with lime crema, and add your favorite toppings. Serve immediately.