Salt & pepper cucumbers
Apple cider vinegar
Red pepper flakes
Dried mustard powder
Sugar (or Demerara)
Clean a jar with hot soapy water and then place in a 275-300F oven to dry and sterilize.
In a small pot, combine a cup of white vinegar and half a cup of apple cider vinegar with a tablespoon and a half of salt, a tablespoon of sugar and then about ⅛ teaspoon turmeric, ⅛ teaspoon dried mustard powder, ¼ teaspoon red pepper flakes, and ½ teaspoon each celery seeds and coriander seeds. (But all of that is up to you--adjust the spices if you wish.) Bring up to a boil and reduce to a simmer for about 10 minutes while you slice the cucumbers and onion.
Thinly slice the cucumbers and onion.
Turn the oven off, carefully remove the jar, pack with the cucumber and onion slices (alternating layers) and then pour the vinegar solution over. Place the lid on top but do not tighten. Allow the jar to fully cool and place in the fridge. Beginning enjoying after 24 hours.