Cook the beetroot in a pot of boiling water until tender. When cool enough to handle, peel and coarsely chop.
Combine the beetroot and onion with vinegar, sugar, salt, the spices and pepper. Then transfer the mixture to a pot and gently simmer for about 30 mins. (If the mixture is too thin, combine the flour with a little water, before mixing it in and cooking for another 10 mins or so.)