Yield: 8 x half-litre (US pint) jars or 4 litre (US quart) jars
Mix vinegar, water and sugar in a large pot. Add spice bag. Bring to a boil. Add onion (if using) and beets, bring back to a boil then lower to a simmer for 5 minutes.
To each half-litre (1 US pint) jar add: 1/2 teaspoon salt and optionally, 1/4 teaspoon Pickle Crisp. (Double those quantities for litre / US quart jars).