First, oil a baking dish that will fit your tomatoes snugly, and heat the oven to 325˚F / 160˚C.
Core the tomatoes, and slice them in half horizontally. Put them in an oiled baking dish, cut side up.
Mince the garlic finely, then mix it with oil, minced herbs, and salt, or use a tiny food chopper to make a garlic/herb paste. Smear this over the top of each tomato half; use it all.
Bake at 325º about 2 hours. The tomatoes will eventually exude juices and collapse, and then will begin to caramelize. Expect some dark bits on the dish itself, but don’t let the garlic burn.
Let the tomatoes cool, then pack them in a single layer in a storage container. Add any oil that’s been left in the baking dish, it’s full of flavor.