Wash 2 large Kilner jars and lids thoroughly, then sterilise by scalding with boiling water. Place a stainless-steel spoon in each jar before adding the boiling water to help prevent the glass from cracking. Carefully drain and allow to air dry.
Add the vinegar, water, salt and sugar to a small saucepan. Gently heat, stirring until the salt and sugar have dissolved, then bring just to the boil and turn off to cool a little.
In a large bowl, mix the sliced courgette, onion, garlic, chilli and spices, tossing well to make sure everything is evenly combined. Pack the mixture tightly into the sterilised Kilner jars.
Carefully pour the hot pickling liquid over the vegetables, making sure they are completely covered. Gently tap the jars on the worktop to release any air bubbles trapped between the vegetables.
Leave the lid slightly ajar until completely cooled, then seal and transfer to the fridge. It’s ready to eat after 24 hours, but I prefer it after a couple of weeks, when the vinegar has mellowed, and all those lovely flavours have had time to come together.