Chop tomatoes and in a food processor puree with vinegar, sugar, and lemon juice until smooth. Pour puree through a sieve into a bowl, pressing hard on solids. Discard solids. Stir in ice water and salt and pepper to taste. Soup may be made 1 day ahead and chilled, covered. Reseason soup before serving.
Stir tarragon into soup and thinly slice cherry tomatoes.
Serve soup sprinkles with tomatoes, zucchini, and onion, and with toasts on the side.
recipe courtesy of Gourmet Magazine