Trim the tops from the heads of garlic. Peel off all but one layer of the outer skin. Set aside.
In a saucepan, combine the vinegar, sugar, peppercorns, cloves, bay leaf, chile peppers and lemon zest. Bring to a boil and cook for 2 minutes. Add the garlic, and continue to boil for another 4 minutes. Remove from the heat and let stand overnight at room temperature.
Transfer to a clean jar. Strain the brine into the jar with the garlic so that the heads are completely covered. Discard the solids. Cover and store in the refrigerator until using. It will keep for 6 to 8 weeks. To keep longer, store in sterile jars and process in a hot water bath for at least 10 minutes to seal the jars.