Homemade Ketchup from Fresh Tomatoes
Homemade ketchup is tomatoes reduced over low heat for at least an hour with vinegar, sugar and spices. The reduction is the whole technique — the tomatoes lose 70% of their water and the flavour concentrates. It keeps a month in the fridge and no longer, because there are no preservatives.
- Prep
- 15 min
- Cook
- 75 min
- Total
- 90 min
- Calories
- 30
Shop ketchup contains far more sugar than most people realise. The homemade version takes time, but every ingredient in it is one you recognise, and the flavour is deeper and much less sweet.
Method
-
1
Peel the tomatoes
Cut a small cross in the base of each tomato, dip them in boiling water for 30 seconds and then into iced water. The skins slip off by hand with no effort.
⏱ 12 min -
2
First cook
Chop the tomatoes and put them with the onion and garlic in a heavy pot over medium heat for 20 minutes until they collapse completely and release their liquid.
⏱ 20 min -
3
Strain
Blitz the mixture with a stick blender and pass it through a fine sieve to remove seeds and fibre. This is what gives the smooth, shop-bought texture.
⏱ 8 min -
4
Reduce
Return the strained purée to low heat with the vinegar, sugar and spices, and leave it for 45 to 60 minutes, stirring every ten minutes, until it halves in volume and thickens.
⏱ 55 min -
5
Test and store
Put a spoonful on a cold plate — if it does not run, it is ready. Pour it hot into a sterilised jar, seal immediately, and cool before refrigerating.
⏱ 6 min
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Tips that actually matter
- There is no shortcut to the long reduction — unreduced ketchup stays thin and tastes weak.
- Very ripe tomatoes are sweeter and need less sugar; firm ones give a sharp ketchup.
- The cold-plate test is more reliable than looking, since ketchup thickens as it cools — do not wait for it to look thick in the pot.
- It keeps a month in a sterilised jar in the fridge. With no preservatives, it will not last like the shop version.
People also ask
Why is my ketchup thin?
It was not reduced enough. The tomatoes need to lose roughly 70% of their water, which takes 45 to 60 minutes over low heat. The cold-plate test is the right measure.
How long does it keep?
A month in a sealed sterilised jar in the fridge. Without preservatives its life is far shorter than the shop version — discard it at any odd smell or sign of mould.
Can I use tomato paste instead?
Yes, and it saves a lot of time: 4 tablespoons of paste plus a cup of water with the same vinegar, sugar and spices, reduced for just 15 minutes. The flavour is less deep than with fresh tomatoes.
Cook mode
Homemade Ketchup from Fresh Tomatoes
-
1
Peel the tomatoes
Cut a small cross in the base of each tomato, dip them in boiling water for 30 seconds and then into iced water. The skins slip off by hand with no effort.
-
2
First cook
Chop the tomatoes and put them with the onion and garlic in a heavy pot over medium heat for 20 minutes until they collapse completely and release their liquid.
-
3
Strain
Blitz the mixture with a stick blender and pass it through a fine sieve to remove seeds and fibre. This is what gives the smooth, shop-bought texture.
-
4
Reduce
Return the strained purée to low heat with the vinegar, sugar and spices, and leave it for 45 to 60 minutes, stirring every ten minutes, until it halves in volume and thickens.
-
5
Test and store
Put a spoonful on a cold plate — if it does not run, it is ready. Pour it hot into a sterilised jar, seal immediately, and cool before refrigerating.
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