Grilled Fish Tacos

Name: Grilled Fish Tacos
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; 1 teaspoon sugar; ⅛ teaspoon salt; Freshly ground pepper; 3 cups finely shredded red or green cabbage; 12 corn tortillas, warmed (see Tip)