Gather all ingredients.

Place eggs into a large pot and cover with cold water. Bring water to a boil, then immediately remove from the heat. Cover the pot and let eggs stand in hot water for 10 to 12 minutes.

Transfer eggs to a strainer and run under cold water for 1 minute. Return eggs to the pot; fill with cold water and let sit until cool enough to handle, 2 to 3 minutes. Peel eggs and place into a 1-quart, wide-mouth jar.

Combine vinegar, water, all but a few slices onion, salt, pickling spice, and peppercorns in a saucepan. Bring to a rolling boil.

Pour over the eggs in the jar. Place remaining onion slices on top and seal the jar. Cool to room temperature, about 1 hour, then refrigerate for 3 days before serving.