Preheat the oven to 225 degrees F. Rinse and dry the tomatoes, then spread onto a large baking sheet. Add the thyme, basil and garlic to the pan, then drizzle with 3 tablespoons olive oil and toss with your hands, making sure everything is coated, especially the garlic and herbs to keep them from getting crispy.
Sprinkle with salt and pepper, then give a good stir to coat everything. Roast for 2 1/2 hours, stirring a few times throughout, or until tomatoes are blistered and shrunken as shown above.
Taste one and sprinkle with a little more salt if needed. Remove garlic and herbs, as they can spoil and are not safe for preserving, then add the tomatoes to a sterilized jar.
Cover completely with olive oil and store in the refrigerator for up to 18 days, just make sure they stay completely submerged in the oil. The olive oil will harden in the refrigerator, which is fine, just let sit out before serving and it will return to liquid.