Soak two bamboo skewers in water for 10 to 15 minutes.
Set aside 6 zucchini 1⁄4"-thick rounds. Cut the remaining zucchini rounds into quarters and toss with the quartered cherry tomatoes, 1 teaspoon of the oil, and the garlic. Season with salt and pepper. Set aside.
Preheat a nonstick grill pan over medium heat. Thread 1 skewer with 1 whole tomato, 1 zucchini round, and 1 beef cube. Repeat two more times, ending with a tomato. Thread the remaining tomatoes, zucchini rounds, and beef cubes onto the other skewer. Drizzle the skewers with the remaining 1 teaspoon oil, turning to coat both sides. Season with salt and pepper.
Place the kebabs in the center of the grill pan and cook for 6 minutes.
Add the reserved vegetables to one side of the grill pan and flip the kebabs. Cook the kebabs for 5 to 6 minutes for medium, turning on all sides to ensure doneness, and cook the vegetables, stirring, until softened. Stir the basil in with the vegetables. Transfer the kebabs and vegetables to a serving plate.