In 2 (9-by-13-inch) pans, place tomato halves, cut-side up. Sprinkle with oil, salt, pepper, onion, garlic, and herbs, and bake for 2 hours. Check the tomatoes after 1 hour, and turn down the heat if they seem to be cooking too quickly. After 2 hours, turn the oven to 400ºF and bake another 30 minutes.
Remove tomatoes from the oven and process through a food mill on medium dye setting over a small saucepan. Discard the skins. Add the white wine and bring to a boil. Reduce heat to low and cook for 5 minutes.
Serve immediately or let cool to room temperature, seal in an airtight container, and freeze for up to 1 year.