Cut an X in bottom of each tomato with a sharp paring knife and blanch tomatoes together in a 6- to 8-quart pot of boiling water, 10 seconds. Transfer tomatoes to a bowl of ice water to cool. Peel off skin with paring knife, beginning from scored end, and discard. Coarsely chop tomatoes. Cook sugar in a dry 2-quart heavy saucepan over moderate heat, undisturbed, until it begins to melt. Continue to cook, stirring, until sugar melts into a golden caramel. Remove from heat and carefully add vinegars. Stir in remaining ingredients and simmer, uncovered, stirring occasionally, until thickened, about 1 1/2 hours. Discard star anise.