To sterilise jars: Wash the jars and lids thoroughly with hot soapy water. Rinse and turn upside down to drain off. Turn the jars the right way up, and place on a baking tray. Pop into a pre-heat 180C/350F/Gas 4 for 15 minutes. Meanwhile, the lids go into hot, simmering water on the stove top for the same amount of time. Take the jars out of the oven to cool before using. And dry the lids by placing on a clean tea towel. Time taken: 15 minutes to sterilise jars. 15 minutes to cook fruit. 5 minutes to boil jam. 1 hour cooling. Makes about 1.5kg of jam.