Cut the onions in half and detach the petals, then cut each petal lengthwise in stripes.
In a medium saucepan, add the water, vinegar, sugar, salt and the olive oil. Heat until starts to boil.
Add the onions to the mixture in the pan and leave for exactly 30 seconds over medium heat.
In a clean and dry jar, add the pickled onions first and place the fresh thyme brunches, topping up with the remaining solution and leave it to cool before closing the lid.
Close the lid and place in the refrigerator before use.
How to sterilize jars: Wash with soapy water and rinse very well. Boil the jars and lids in a large pan for 5 minutes and allow it to dry completely.Storage: Homemade pickled onions will last for up to 3 weeks in the fridge.