Combine all ingredients except the sugar in a 2-qt. saucepan; boil. Reduce heat; simmer for 10 minutes.
Meanwhile, cook sugar in a skillet over medium-high heat until it becomes dark amber and syrupy, about 5 minutes. Add caramelized sugar to vinegar mixture and whisk to combine; cook sauce for 5 minutes; transfer sauce to a glass jar with a tight-fitting lid.
Refrigerate, covered, for 3 weeks; strain to remove solids; return to jar. Refrigerate for up to 8 months.
I have used this before the suggested 3 weeks with good results, though the flavor really seems to improve with time. I usually just pour the amount I need through a strainer so that I can leave all the spices in to continue adding flavor.
