Good news! Pickles (without sugar) and pickled onions are allowed but only as condiments. Beetroot isn't included. Too much of either the onion or pickle will become a vegetable which is not allowed.
They are allowed to add a bit of FLAVOURING - but not as a 'Veg'. SO be really really sparing. Think of a chopped spoonfull or so of onion in your burgers etc.
I've always avoided them on attack / PP