Preheat the oven to 450F or 425F convection (use convection if you have it). Line a rimmed baking sheet with parchment paper.
Cut the fish into 2-inch pieces. Add them to a large bowl along with 2 tablespoons olive oil, spices (cumin, smoked paprika, garlic powder, black pepper, and cayenne, if using) and 1 teaspoon salt. Toss to coat. Sprinkle on the tapioca starch (if using) and toss again. Place the fish pieces on ½ of the baking sheet.
Add the cabbage to the other half and toss with remaining 1 tablespoon olive oil and remaining ½ teaspoon salt. Bake for 10 minutes, or until the fish flakes easily with a fork. If your fish has the skin on, peel it off (it peels off easily once cooked).
Meanwhile, add the cucumber, orange, red onion (if using), lime juice and salt to a medium bowl and toss to coat.
Warm the tortillas on the stove over an open flame or in a pan. Top with cabbage, fish, yogurt (if using), salsa, cilantro, and squeeze of lime.