1. Preheat the oven to 350°F. 2. On a sheet pan, roast the tomatoes, garlic, and onion until tender and lightly browned, about 15 minutes. Transfer them along with the chiles and vinegar to the jar of an electric blender and puree until smooth. 3. Pour the mixture into a medium-size saucepan and gently simmer for about 20 minutes; season to taste with salt and reserve.