In a small, heavy-bottomed saucepan with a well-fitting lid, combine all the ingredients. Over low heat, bring to the lightest of boils, then lower to the lowest heat setting. Cook for about an hour with the lid in place. Be careful not to breathe the vapors, which are irritating.
After an hour of cooking, remove the pan from the heat and let the contents steep, covered, for another hour.
Pour the entire contents into a 12-ounce, processed canning jar. The peppercorns can be used immediately, or stored in the refrigerator.