To sterilise the jars, choose one of the methods below:
Run jars through the dishwasher, keep the door closed and do not remove till ready to use.
Wash with hot soapy water and place into oven at 150C for 15 minutes. Remove using oven mitts.
Wash with hot soapy water and place in a boiling water bath for 3-5 minutes. Remove with tongs.
Wash the lids with soapy water, leave in a bowl with hot water till you are ready to use.
To make spaghetti in tomato sauce
Roughly chop the onions.
Wash and chop the tomatoes into quarters. Place the tomatoes and onions into a food processor and blitz.
Transfer the onion and tomato mixture to a large pot. Cook for 15 – 20 minutes, bring to the boil.
Fill a large pot with boiling water, add in the pasta and cook for 10 minutes.
Drain the pasta and add to the tomato sauce. Cook for a further 30 minutes, stirring often as the pasta may stick to the bottom of the pot. Remove from the heat.
Remove the warm jars from the dishwasher, oven or pot before using. Fill each jar to the top. Run a butter knife around the top of the jar to remove any bubbles and clean the top of the jar.
Close the lid. Repeat till all jars have been filled.