Preheat the oven to 375°F.

Combine the tomatoes, olive oil, and thyme on a baking sheet. Sprinkle with a generous amount of salt and pepper and toss to coat. Arrange the tomatoes, cut side down, in a single layer. Roast for 30 minutes. Scatter the sliced garlic over the tomatoes. Roast for another 25 to 30 minutes, until the tomatoes are tender, wrinkled, and beginning to brown. (There will be a lot of liquid on the baking sheet. Don't worry.)

Remove the baking sheet from the oven and let the tomatoes cool slightly. If you can, peel the skins off the tomatoes and discard. If the skins won't budge, it's not a big deal. Your confit will still be delicious.

Transfer the tomatoes, garlic, and accumulated juices to a large bowl and stir in the vinegar and 1/2 teaspoon of sugar. Using a wooden spoon, mash the tomatoes into a chunky sauce. Taste the confit and add more salt, pepper to taste.