To pickle eggs in vinegar, place 12 hard-boiled, peeled eggs in an airtight container or divided among several lidded jars. Pour a vinegar-based pickling mixture over the eggs to cover them. Seal the container, and store it in the refrigerator for at least two weeks while the eggs pickle.
Make the vinegar-based pickling mixture by combining 2 cups of vinegar with 1 cup of water, 2 teaspoons pickling spice, 1 teaspoon salt and 1 teaspoon sugar. Add the ingredients to a saucepan along with optional flavor enhancers, such as chopped onion and minced garlic. Bring the mixture to a boil over medium-high heat. Turn the heat down to medium-low, and simmer the pickling liquid for approximately 10 minutes to allow the flavors to combine. Take it off the heat, and let it cool to room temperature before straining it and pouring it over the eggs.
The type of vinegar used to make the pickling liquid has a substantial impact on the flavor. For example, apple cider and white wine vinegar add mild, well-rounded flavor. Malt and red wine vinegar have harsher flavor and a stronger tang. To color the pickled eggs bright pink, use beet juice vinegar, or simmer the pickling liquid along with 1 small peeled beet cut into chunks.