After 1 minute, drain the onions from the boiling water (keep the water – you will need to use this again) and add them to your 1Ltr clip top jar, with the slices of lime. Using your pan of 500ml boiling water, add the pickling vinegar, coriander, peppercorns, salt and sugar. Boil for 5 minutes and stir to ensure all of the salt and sugar has dissolved. Leave the boiling solution to cool for 10 minutes (don’t pour boiling water directly into your jar), then add to the sliced onion and lime until the liquid level is at the top. Seal the jar and allow to cool before refrigerating – your delicious pickled onions and limes will taste best if left to sit for 24 hours… enjoy!