Bring the vinegar to a boil in a small saucepan over medium heat. Turn the heat to low and reduce by half. Remove from heat and let cool. The vinegar will thicken as it cools. To make ahead, it can be refrigerated in a covered container for up to two weeks and then used on the napoleons when needed.
Spray grill with nonstick cooking spray. Place vegetables on the grill over medium heat and cook until tender, about 10 minutes, turning frequently as the natural sugars will caramelize and burn. Layer eggplant, mushrooms, zucchini, squash, asparagus, peppers and top with steamed Swiss chard. Top with tomato fresco and sprinkle around the plate. Garnish with fresh basil. Serves 4