Cut the root and head off the onions. Remove the skin.
Slice the onions, from top to bottom, as thin or thick as you want
Place onions in mason jars, leaving 1/2 inch headspace
Add two cloves of garlic in each pint jar
Add 1 tsp. of mustard seed to each jar
Add 1 tsp. of peppercorns (if desired)
Customize with your own spcies (if desired)
In a pot, add vinegar, water, sugar, and salt. Bring to a boil
Add boiling vinegar mixture to your jars, leaving 1/2 inch headspace
Use a butterknife to burp the bubbles out of the jars, adding more vinegar as needed. Ensure all ingredients are covered by the mixture in each jar
If you are storing in the fridge, add a fermentation weight to push the veggies down underneath the liquid. Wipe the rim to clean, add a lid and ring, and let sit on counter until cool. Once it reaches room temperature, store in the fridge overnight. Can be used for up to three weeks.
If you are canning for long-term storage, wipe the rim of each jar, add a warmed lid and ring, and place in the water bath canner or large pot full of water. Water should be at least 2 inches above the jars. Bring to a boil and process for 10 minutes. Remove from pot using a jar lifter, place on a towel, and allow to cool for 24 hours. Check your seal to ensure processing was successful. Onions are now shelf stable for up to 18 months.