1
Char peppers over gas flame or in broiler until blackened on all sides. Enclose in paper bag and let stand 10 minutes. Peel, seed and slice peppers.
2
Heat oil in heavy large saucepan over medium heat. Add shallots, garlic and thyme and sauté 3 minutes. Add 3 cups broth and all but 4 slices of roasted pepper. Simmer uncovered until peppers are very soft, about 20 minutes.
3
Working in batches, purée soup in blender until smooth. Return to same pot. Add half and half, vinegar and cayenne pepper. Rewarm soup, thinning with additional broth, if desired.
4
Season to taste with salt and pepper. Ladle soup into bowls. Garnish with reserved pepper strips and basil.
