- Wash Mason-type jars and place them upright in a large pot. Fill pot and jars with water and bring to a simmer over medium heat. Turn off heat and let jars stand in hot water until ready to be filled. (Jars can also be washed and kept in dishwasher until ready to be filled.)
- Place lids in a small saucepan filled with water. Bring to a boil over high heat and then turn off heat so seals soften. Use new lids only. Metal rings can be reused.
- Cut onions in half, quarters, or large strips, however you wish.
- In a large saucepan, combine onions, water, vinegar, celery salt, sugar, and salt and bring to a boil for 2 minutes over high heat. Divide into jars, making sure to leave 1 cm (½ in.) of space between lid and top of mixture.
- Remove air bubbles by stirring along sides of jar and between ingredients with a wooden or rubber spoon. Wipe jar rims, cover with lids, and lightly screw on rings.
- Place jars upright in pot and add water as needed to cover jars with at least 2.5 cm (1 in.) of water. Bring to a boil over high heat for 15 minutes. (Start timer when water reaches a rolling boil.)
- Remove jars from pot, place upright, and let cool for 24 hours. Lids must pop to seal shut.
Want to make larger quantities? No problem! Simply multiply all the ingredients listed. Make sure to maintain vinegar/water/sugar ratios. Seasonings can be adjusted to taste.