Second time in a month I've prepared this!
My grannie's simple recipe:
1 lb cooked quartered & sliced (Belgian organic) beetroot
1 large quartered & sliced (Belgian organic) onion
2 tsp Demerara sugar
1/4 pint wine vinegar (gran would have used malt)
1/4 pint warm water
Mix & mix & mix...
Tomorrow the onions will be the same colour as the beetroot.