Brush the halibut on both sides with tandoori paste. Cover and marinate in the fridge 30 minutes. Combine the yogurt, cucumber, green onion, chili flakes, salt, pepper and lime juice in a bowl. Cover and store in the fridge until the fish is ready. Preheat oven to 450F. Place fish on a parchment-lined or non-stick baking sheet. Bake 12-15 minutes, or until cooked through. Place the fish on plates and serve a small bowl of the raita alongside for dipping.