I want to try to pickle some onions to eat with marinated herring--
I have a brainstorm that I'm going to try to pickle them in just salt water, no vinegar. They do this with cucumbers (Half-sour) so why not onions?
I was thinking to get them going for 2 days at room temp and then change the brine and refrigerate for a week. Grand experiment.
I would find a fermented pickle recipe and follow that. I have no idea if it will work--is there something about cucumbers that supports fermentation that onions do not possess?
I'd use a 2% brine and leave it for 3-10 days ( until the fermentation has obviously ended) at room temp ( 68-72 degrees) in the dark ( light kills lactic acid bacteria) in a non reactive container that is air locked and then put it in the fridge for another 1-4 weeks, until it no longer tastes salty.
Check out pickl-it.com for info on how to ferment almost anything. Her methods are the only ones I've used that are consistently good.
Quick pickled onions are popular throughout Latin America, though I don't know if this style would go with herring. The onions are sliced, blanched briefly, and then left to sit with salt and lime juice (a few hours to a day). Red onions are preferred because the end product is a pretty pink.
If pickling/fermenting in a brine, a 5% salt by weight to water by weight ratio is correct. Use 2% salt when pickling packed/sliced like sauerkraut. You may want to use some whey liquid from yogurt as a starter.
I've found that with onions, using a vinegar pickling brine with herbs and spices, tastes better. Even then they really need 2-3 months to hit perfection. I have used variations on English pickled onion recipes.