Ingredients

• 4 teaspoons chili powder, preferably made with new mexico or ancho chiles (see note)
• 2 tablespoons lime juice
• 2 tablespoons extra-virgin olive oil
• 1 teaspoon ground cumin
• 1 teaspoon onion powder
• 1 teaspoon garlic powder
• 1 teaspoon salt
• ½ teaspoon freshly ground pepper
• 2 pounds mahi-mahi or pacific halibut (see note), 1/2-3/4 inch thick, skinned and cut into 4 portions
• ¼ cup reduced-fat sour cream
• ¼ cup low-fat mayonnaise
• 2 tablespoons chopped fresh cilantro
• 1 teaspoon lime zest
• 2 tablespoons lime juice
• 1 teaspoon sugar
• ⅛ teaspoon salt
• freshly ground pepper
• 3 cups finely shredded red or green cabbage
• 12 medium corn tortillas, warmed (see tip)