Preheat your grill to high heat. Spray a grill basket with cooking spray.
Add all of the ingredients for the marinade into a large bowl and whisk together.
1/3 cup balsamic vinegar, 1/3 cup olive oil, 1 Tablespoon honey, 2 teaspoon garlic, 1/2 teaspoon salt, 1/2 teaspoon ground black pepper, 1/2 teaspoon red pepper flakes (optional), 1 teaspoon Italian seasoning
Add all of the chopped veggies to the bowl (not the whole cherry tomatoes) and toss to coat the veggies in the marinade.
2 red bell peppers, seeds removed, sliced into thick pieces, 2 yellow bell peppers, seeds removed, sliced into thick pieces, 1 medium eggplant, peeled, sliced, into 1/4 inch rounds, 2 medium zucchini, sliced into 1/4 inch rounds, 2 portobello mushrooms, sliced into 1/4 inch strips
Move the marinated veggies to the grill basket, scooping the veggies out of the bowl with tongs or a spoon so you can reserve the rest of the marinade in the bottom of the bowl. Save any of the marinade in the bowl for after the veggies have cooked.
Place the grill basket on the grill and grill the veggies, tossing them with tongs every minute. Let the veggies grill for about 6 minutes, then add the cherry tomatoes to the grill basket, toss well, and grill for another 2 minutes.
2 cups cherry tomatoes, whole
Remove the veggie from the grill basket and toss them back into the bowl of the marinade (it is totally safe to use the same marinade with veggies!).
Serve the veggie while warm.