Preheat a grill over medium high heat and rub the grill grates with olive oil.
Cut the tomatoes in half widthwise (through the center of the tomato).
Drizzle the cut side of the tomatoes with olive oil and season with the garlic powder, salt and pepper.
Place the tomatoes on the grill (directly on the grill grates) cut side down. Grill for 4-6 minutes with the lid closed until grill marks are visible on the tomatoes.
Carefully flip the tomatoes and grill for 2-3 more minutes.
Carefully remove the tomatoes from the grill.
Serve topped with the fresh basil leaves and enjoy!
Notes
Leftover grilled tomatoes will last for 3-4 days refrigerated in an airtight container. Beefsteak tomatoes also work great for this recipe.