Step 1 Cut the fillets into equal-sized pieces about as wide as a slice of prosciutto. Because of the size of a halibut fillet, you will probably end up cutting across the fillet, making pieces that are roughly square.
Step 2 Lightly salt and pepper the fish. Lay a prosciutto slice on the work surface and put a piece of halibut in the middle of it. Fold the ends around the halibut. It will look a little messy on the side where the ends meet, but don't worry; you'll serve it with that side down. Refrigerate the halibut until ready to cook.
Step 3Cut the tomatoes in half and place them in a bowl. Add three-fourths teaspoon salt and toss to coat well. Set aside to let the salt draw out some of the tomato juice.
Step 4When you're ready to cook the fish, soak about 1 cup of wood chips in water to cover. Light the coals in a chimney and when the coals are glowing hot, empty them into the center of the grill. If there aren't enough coals, add more on top and wait until they are glowing as well. Drain the wood chips and place on top of the coals.
Step 5Toss the tomatoes with the basil, olive oil and vinegar.
Step 6Spray a grill basket with nonstick cooking spray or rub lightly with oil. Place the halibut packages in the basket and place over the fire. Cook, uncovered, on one side until the prosciutto has lightly crisped, 4 to 5 minutes. Turn and cook until a knife inserts easily into an uncovered part of the halibut, another 4 to 5 minutes. Don't overcook the halibut; even with the prosciutto wrapping, it will dry out pretty quickly. Total cooking time should be about 10 minutes.
Step 7Carefully open the grill basket, making sure the prosciutto doesn't stick to it. Place the halibut packages on a large platter with the neatest side facing up. Spoon the tomato salad around the outside of the platter, sprinkle with black pepper and serve immediately.