Place the vegetables on the grill grates in one single layer.
Close the lid and cook for 10 to 12 minutes, flipping once halfway through cooking. When done, the veggies should be tender with visible grill marks. If they aren’t soft enough, or cooked to your liking, give them a minute or two longer to cook.
In the meantime, in a mixing bowl combine lemon juice, olive oil, garlic, Italian seasoning, sugar, salt, and pepper; whisk until thoroughly incorporated. Taste and adjust seasoning. Set aside.
Remove veggies from grill and transfer them to a serving bowl.
Pour the prepared dressing over the vegetables; toss gently to combine.