Wash and trim the beetroot. Slice to final size, coat in oil. Roast in covered casserole dish or roasting tin 200°C for 1 hour or until tender.
Pickling vinegar, put whole spices in a medium saucepan. Toast over a low heat until they begin to smell aromatic. Add the bay, pour in all of the vinegar and sugar, let it dissolve, and bring to a simmer.
Pack the beets into sterilised jars, add 1 tsp coarse crystal sea salt to each, then pour over the hot vinegar and seal. Ready to eat in 2 weeks, or longer.