I didn't grow that beetroot, but I did pickle it with plain white vinegar and a little sugar. I don't even heat the vinegar. Straight in the clean jars and it's never failed me in 40 years.
I have one beet growing in the garden, the only survivor of a small row I sowed. Whatever *shrug*, It's gonna get eaten when it's large enough.
I used to do pickled shallots too, clean them off, place on a large platter, salt them well and cover. Yes, cover, because they will stink your house out from top to bottom. The day after, rinse the shallots and place them in jars, tip in a spoonful of pickling spice, top up with white vinegar. In a few weeks, they will be crunchy and crisp, please, never water bath onions, you will ruin them.