Preparation

• Combine all the ingredients in a small saucepan. Bring to a boil over medium-high heat, cover, and simmer over medium to medium-low heat until the onions are mostly translucent and the juices are beginning to thicken, about 5 minutes. Uncover and simmer, stirring frequently with a heatproof spatula, until very thick, another 6 to 8 minutes. Let cool completely in the pan before storing in an airtight container in the refrigerator for up to 2 weeks.