This recipe can be prepared over several days. After pureeing the marinated tomatoes, allow them to drain overnight; store extracted juices in the refrigerator for up to one day.
Make the tomato essence: In a large bowl, combine tomatoes, celery, shallot, fennel, thyme, tarragon, 4 tablespoons basil, garlic clove, 1 tablespoon salt, cayenne, Worcestershire, and hot-pepper sauce. Cover, and marinate 4 hours.
Transfer to bowl of food processor; pulse to combine, about 5 seconds. Do not overblend. Drape two 14-inch squares of cheesecloth over a deep bowl or stockpot, and transfer mixture to the cheesecloth. Tie ends together tightly, and suspend over bowl to catch juices, preferably overnight. Transfer juices to an airtight container, and store in refrigerator until needed, up to 1 day. Discard contents in cheesecloth.
Make the timbales: Fill a medium saucepan halfway with water, and bring to a boil over high heat. Score an X in the bottom of each large tomato; place in boiling water for 10 seconds. Remove with a slotted spoon, and let cool slightly. Use a paring knife to gently remove skins and cut flesh into petals by following the shape of the tomato from top to bottom. You should have four petals from each tomato for a total of sixteen; set aside.
Remove and discard seeds from core of tomatoes, and dice remaining flesh. Combine diced tomatoes in a small bowl with remaining 1/2 garlic clove, 2 tablespoons chopped basil, 1/4 teaspoon salt, 1/8 teaspoon pepper, and balsamic vinegar; set aside. Using a 2-inch round cutter, cut out eight circles from eight petals, and place one each in the bottom of four sterilized 4-ounce jelly jars, presentation side down. Set aside remaining four circles. Dice the scraps, and add to the marinating diced mixture.
Fit two of eight remaining petals to line sides of each jar, overlapping slightly to cover. Place 4 to 5 tablespoons diced tomato mixture in each jar to fill, and place one of the reserved circles on top. Press down lid; screw on ring lid. Place in refrigerator 1 hour or overnight.
In a small bowl, whisk water, sherry vinegar, sugar, and remaining 1/2 teaspoon salt and 1/8 teaspoon pepper. Set aside.
Cut off ends of zucchini and eggplant. Use a paring knife to slice lengthwise into 1/4-inch-thick strips; cut each strip into 1-inch squares. In a medium saute pan, heat oil over medium heat. Add eggplant skin side down; cook 30 seconds. Add zucchini skin side down, and cook 1 minute on each side. Pour sherry-vinegar solution into pan, and remove from heat.
Remove jars from refrigerator; run the tip of a paring knife around the inside of each jar to loosen, and unmold. Place a timbale in the center of each of four chilled bowls. Surround with eggplant and zucchini. Ladle tomato essence around bowl; drizzle with olive oil. Place a scoop of sorbet on each timbale, and garnish with basil. Serve immediately.