Preheat oven to 425°F. Line a rimmed baking sheet with foil; brush with 2 Tbsp. oil.

Stir together chili powder, paprika, cumin, onion powder, and ½ tsp. each salt and black pepper in a small bowl.

Arrange fish fillets on prepared baking sheet. Drizzle 1 Tbsp. oil over fish; rub or brush to coat. Sprinkle spice mixture evenly over both sides of fillets.

Bake until fish flakes easily with a fork and edges are caramelized, 10 to 12 minutes.

Meanwhile, for slaw, toss together coleslaw mix, chopped cilantro, jalapeño, lime juice, vinegar, garlic powder, ¼ tsp. salt, and remaining 2 Tbsp. oil in a large bowl.

For chipotle sour cream, stir together sour cream, chipotle pepper, adobo sauce, and remaining ¼ tsp. salt in a bowl.

Flake fish into bite-size pieces. Divide fish and slaw evenly among tortillas and top with chipotle sour cream. Garnish with cilantro and serve with limes.