Fish Tacos - Fresh Grilled Grouper Tacos

Ingredients

• 1/4 cup low-fat sour cream
• 3 1/2 tablespoons fresh lime juice, divided
• 2 small plum tomatoes, seeded and diced
• 2 1/2 tablespoons olive oil, divided
• 2 tablespoons chopped fresh cilantro
• 1 teaspoon minced seeded jalapeño pepper
• 3/4 teaspoon salt, divided
• 1/4 teaspoon freshly ground black pepper, divided
• 1 1/2 cups thinly sliced red onion
• 8 (6-inch) tortillas
• 1 pound grouper or other firm white fish fillets
• 1/2 teaspoon chili powder
• 1/4 teaspoon cumin
• Non-stick cooking spray
• 2 cups shredded red cabbage or shredded romaine