Wash and halve the tomatoes lengthwise and place in a bowl. Combine the remaining ingredients. and pour over the tomatoes. Marinate at least 2 hours or overnight, in the refrigerator. Drain and reserve the marinade to use again. It will keep, refrigerated, for 10 days.
Preheat the oven to 300 F/150C.
Place the tomatoes, cut-side up, on a baking pan covered with foil. Bake until slightly shriveled but not completely dried out, about 1 to 1 1/2 hours – longer if they came out of the refrigerator.
Oven-roasted tomatoes can be stored in a covered container in the refrigerator for at least 1 week.