Slice the red onions thinly
Put all the red onions in a jar or bowl with a lid. I use a mason jar
Add the remaining ingredients into the jar over your sliced onions, making sure they are immersed in the liquid. If they are not immersed, add more water
Cover and shake the jar or container really well to combine all of the ingredients. If you can't shake your container without making a mess, add all of the ingredients to a large bowl, mix well, then add back to your container of choice.
Cover and place in the fridge. They will be ready to eat in about 10-12 hours or when the brine starts to turn bright pink. They can be stored in the fridge for up to three weeks.