Wash the beetroot thoroughly and cut off any LONG bits but leave the ends on - as per the photo.
Put them in a pot and cover completely with water.
Bring to the boil, turn heat down and simmer for between 45 minutes and 55 minutes with the lid on. Check after about 30 minutes to make sure the water has not evaporated, and if it has, add a bit more.
Pierce with a fork so you can tell when they are just tender.
Leave to cool and then pour the liquid into a Tupperware or dish. Add a teaspoon of sugar (if you like it sweet you can add more) and top the liquid up with about 4 tbsp of vinegar. This will also make it last longer.
Slice the beetroot and carefully drop into the liquid.
Put in fridge ready to be used whenever you need it.