I used 3 onions and substituted red wine vinegar for white, better flavor, in my opinion. I also added 4 crushed cloves of garlic, 1 Tbs whole peppercorn, and 1 Thai Chili for a little heat.
There is still so much pickling liquid left over after this.
I added the hot brine right to the onions so it would pickle better. If you are adding cold brine, as suggested, I would salt the onions for 15 minutes, then rinse. Otherwise, the brine won't really pickle the onions properly. Use about 1 tsp per onion to remove excess moisture and break down the onions a little.
