To sterilise jars in the oven: Wash the jars and the lids in hot soapy water, rinse, but do not dry them. Stand them on a baking tray while they’re still wet. Place the tray of clean, wet jars and lids into a preheated oven at 180ºC / 350ºF for 15 mins. To sterilise jars in the microwave: Wash the jars and the lids in hot soapy water, rinse, but do not dry them. Place them in the microwave whilst still wet. Microwave on full power for 2 minutes If the lids are made of metal DO NOT MICROWAVE.  Instead, place the lids in a pot of boiling water and boil for 5 minutes.