1. Preheat oven to 120C/Gas 1-2. Lay the tomatoes in a single layer on a sheet pan and sprinkle with the salt. Cook the tomatoes for 5 to 6 hours or until dried and slightly shriveled, but still plump.
2. If not using immediately, store tomatoes in a sealed container in the refrigerator, for 3 to 4 days; or layered in a container with herbs and covered with olive oil. Store, covered in the refrigerator for up to 2 weeks.