1 large onion, sliced into rings
2 cups white wine vinegar
2 cups water
1/2 cup white sugar
1 teaspoon salt
1 tablespoon pickling spice, wrapped in cheesecloth
Cover eggs with water in a large pot. Cover with lid. Bring to a boil over medium-high heat. Boil gently for 10 minutes. Drain. Run cold water over eggs until they are cold. Shell eggs.
Prepare the brine in a sauce pan by combining the vinegar, water, sugar and salt. Stir over medium heat until sugar is dissolved.
Layer the eggs (whole) and onion rings in a sterilized 2 quart jar to within 1 inch of the top.
Add pickling spice to brine. Swirl bag around for 30 seconds. Remove bag. Pour brine over eggs to fill jar with 1/4 inch from top. Seal with a sterilized lid. Store in the refrigerator for 1 to 2 weeks before serving. Serve chilled.