Any number of onions (Pickling only) as long as you have jars for the quantity.
Note: The jars or containers must be sparkling clean and sterilized in the oven.
Put in a basin and cover with brine. Let stand 12 hours at least, then drain.
Wipe the onions and put into jars cover with spiced vinegar and cork or cover well.
The spiced vinegar I use is approx:- 1 Kg.brown sugar, 1 Tablespoon Mustard seeds, two bottles white vinegar 750Ml. The odd clove wouldn't go astray.
Leave for 6 weeks in a dark place
Note.The spiced vinegar must be boiling when covering the onions.