Bring all ingredients to a simmer with 2 cups water in a small saucepan over medium heat, stirring often. Reduce heat to low and cook 5 minutes until most cranberries have burst.
Spoon out a few whole cranberries and set aside for garnishing drinks if you like.*
Strain mixture, pressing liquid out of pulp using the back of a spoon. Discard pulp. Chill at least 1 hour. Store for up to 3 months.
*Roll the berries in sugar, skewer on toothpicks, and set across tops of drinks. Use that day.