Chop the 1kg of red onions into small strips. To quickly do this, I recommend halving your onion then from one side, chopping diagonally so the blade faces the center of core of the onion.

Combine your 350ml of distilled white vinegar and water (equal parts) into your pot. Add your salt and pickling herbs to the liquid. Bring to a boil and take this liquid off the heat immediately after you reach boiling.

Put all your chopped red onions into your mason jar. It may seem like there's not enough space - don't be afraid to compact down your onions a bit to make more room. Once your onions are in the jar, place the mason jar into the sink for pouring (so that you don't splash hot pickling liquid everywhere). Slowly pour in your hot pickling liquid from the pot into the mason jar until the hot liquid covers all the onions. You might have some herbs left over at the bottom of the pot - leave a little room in your mason jar for more pickling liquid, and use a spoon to get all the herbs into the jar.

Now cap your mason jar and throw it in the fridge overnight (or at least 4 hours) for pickling. Remember - you're putting a sealed container full of hot liquid into the fridge - the change in temperature is going to reduce the pressure in the jar, and create a small vacuum. When you open this the next day, the lid may be a bit hard to open due to this vacuum. These onions should be good to sit in your fridge for at least a few months - although they've never lasted more than a week or two for me. Take note, the longer they stay in the pickling liquid, the more tangy and pickled your onions will be!

You can really put these on anything! Here's a collage of a few meals I've added these to. Whenever you need a bit of tang into your meal (to balance out some protein/fat), I highly recommend just adding some of this onto whatever it is you're eating. I've seen people put this on avocado toast, peanut butter (who knew!) etc. Make sure you also utilize the pickling liquid for a nice onion-y zest into whatever might need some acidity - I like to add this pickling liquid into my vinaigrettes for the salads I like to make!