Adjust rack to lower middle position and heat oven to 500 degrees F. Place tomatoes on a large (18- by 12-inch) rimmed baking sheet, which should fit in more or less a single layer. Scatter garlic over tomatoes, then drizzle with olive oil and vinegar and sprinkle with salt and pepper.

Roast until most of the tomato juice has evaporated and some of the tomato skins have started to turn golden brown, about 20 minutes. Let cool and then store in a jar or covered container. (Can be refrigerated for at least a couple of weeks.)