In a large bowl, combine vegetable oil, chili powder, 2 tsp (10 mL) of the lime juice, and salt and pepper to taste; add fish, turning to coat. Place on greased grill over medium-high heat; close lid and grill, turning once, until fish flakes easily when tested, about 6 minutes.
Meanwhile, in another bowl, combine cabbage, yellow pepper, green onions and cilantro with remaining lime juice, and add salt and pepper to taste.
Top tortillas with equal amounts of coleslaw. Break fish into chunks; divide among tortillas. Top with diced avocado and radish slices. Serve with a dollop of light sour cream and a splash of hot sauce, if desired.
Per serving: 361 calories, 26 g protein, 10 g fat (2 g saturated fat), 40 g carbohydrates, 7 g fibre, 40 mg cholesterol, 472 mg sodium.