1. Preheat the oven to 250° F.
2. Line a baking sheet with aluminum foil.
3. Crosswise cut each tomato into 3 slices of 3/4 inch thickness.
4. On the lined baking sheet, arrange the tomato slices in single layer.
5. Roast in oven for 1 3/4 to 2 hours until most of the liquid has caramelized.
6. Use a metal spatula to remove baked tomatoes from the baking sheet.