Place all the ingredients except the sugar and vinegar in a jam pan (I use this) or large pan and bring to the boil.
Then reduce the heat, cover with a lid (I use one like this) and gently simmer for 30 minutes, stirring occasionally until all the vegetables have softened.
Now whiz in a blender until smooth, then sieve over a jug, pressing down until all the juices have passed through and discard the seed pulp you are left with.
Then clean your pan and pour in your tomato juice, vinegar and sugar, and gently heat until all the sugar has dissolved.
Once you have no sugar grit at the bottom of your pan, start boiling your sauce and constantly stir until you have your desired consistency that resembles ketchup (it should reduce a bit).
Mine took about 20 minutes, bearing in mind it should thicken more when it turns cold.
Then, using a funnel, pour in to your sterilized hot jars (while the sauce is hot too) and screw your lid on nice and tight.
Once cooled, store in a cool dark place and refrigerate once opened. It should last up to 6 months.