- In a large preserving pan or heavy pot, combine the diced beetroot, onions, water, vinegar, salt, and spices. 
- Bring to the boil, the turn it down to simmer for 30-40 minutes 
- Once the beets are almost cooked through, add the sugar and stir until it has dissolved. Cook for an additional 10-20 minutes, until the beetroot is tender and fully cooked. 
- To thicken, combine the cornflour and 4 Tbsp water and slowly add it to the beetroot. Stir constantly and it will thicken up and turn all glossy and thick. 
- Follow the water bath canning instructions below if you want to can it. Or just follow instruction six below. 
- Spoon hot relish into sterilized jars ( I use my dishwasher) seal immediately, and allow to cool. 
- Store in a cool, dark place — the flavour deepens beautifully after a week or two.