For the dressing: In a small bowl, whisk together the vinegar, lemon juice, and olive oil. Season to taste with salt and pepper. Set aside until ready to use.
Preheat oven to 425 degrees F.
For the salad: Cut 1/2-inch off the tops of the heads of garlic, so the cloves are just visible. Rub the heads of garlic, bell peppers and tomatoes with olive oil to coat them. With a paring knife, cut a cross across the stem end of each tomato. Place all the vegetables on a baking sheet and roast for 30 to 40 minutes, turning every 10 minutes.
Immediately place all the vegetables in a large bowl, cover with plastic wrap and leave to cool, about 30 minutes. Peel the peppers and tomatoes, remove the seeds, and cut vegetables into strips. Squeeze the garlic cloves from their skins. Arrange the vegetables on a large serving platter, or on individual plates, season with salt and pepper to taste, and drizzle with the reserved dressing.
c.1997, M.S. Milliken & S. Feniger, all rights reserved