Boil the beets: Place beets in a large pot, cover with water, and boil until tender (about 30–40 minutes). Drain and let cool.
Peel and slice: Once cool, peel the skins off (they should slide off easily). Slice into rounds or wedges.
Prepare the brine: In a saucepan, combine vinegar, water, sugar, salt, and optional spices. Bring to a boil, stirring until sugar dissolves.
Pack the jars: Add sliced beets to sterilized mason jars. Pour the hot brine over them, leaving about 1/2 inch of headspace.
Seal and chill: Seal the jars with lids. Let cool, then refrigerate for at least 24 hours before eating. (They taste even better after a few days!)
Keeps up to 4–6 weeks in the fridge.
