Preheat oven to 475 degrees F. Place a wire rack on a rimmed baking sheet; coat with cooking spray.
Coat fish with ¼ cup mayonnaise. Place panko in a shallow dish and roll the fish in it. Transfer to the rack on the pan. Bake the fish until crispy and cooked through, 8 to 12 minutes, depending on thickness.
Meanwhile, mix the remaining ¼ cup mayonnaise, sour cream, adobo sauce, lime juice and pinch of salt in a small bowl.
Sprinkle the fish with the remaining ¼ teaspoon salt and pepper. Divide rice among 4 bowls and top with the fish, cabbage, radishes, the sauce and cilantro, if desired.