In a small saucepan bring the vinegar to a boil over medium heat.
Reduce the heat to low and simmer until reduced to 2 tablespoons.
(It will resemble molasses.) Remove from the heat and use a rubber spatula to scrape the vinegar reduction into a small bowl.
Stir in the ketchup, oil, and Tabasco.
Transfer to a clean jar with a tight-fitting lid.
Store in the refrigerator for up to 3 weeks.