In a very clean 1-qt glass jar combine the rosemary leaves, the garlic, and the vinegar and let the mixture steep, covered with the lid, in a cool dark place for at lease 4 days and up to 2 weeks, depending on the strength desired.
Strain the vinegar through a fine sieve into a glass pitcher, reserving the garlic and discarding the rosemary leaves, and pour it into 2 very clean 1/2 pint glass jars.
Add a rosemary sprig and some of the reserved garlic to each jar and seal the jars with the lids.
Once steeped, this vinegar is supposed to keep for several months. Garnishes and other solids left in the jar, however, may discolor or break down.
Servings: