How to preserve tomatoes

  • Heat oven to 90-100 degrees Celsius. Wash jars with warm soapy water, rinse and leave to dry upside down on a tea towel. Place jars up the right way, not touching each other, into the heated oven for at least 20 minutes to sterilise them. Put the lids in a pan of boiling water for around 5 minutes to sterilise them.
  • Next, with a sharp knife, put a good-sized cross in each tomato at the stem end. At the same time put a large pot of water on to boil, and prepare a bowl of water with a good lot of ice in it.
  • Place the tomatoes in the boiling water for around 30 seconds, then using your slotted spoon, scoop them out of the boiling water and straight into the iced water.
  • As soon as they’re cool enough to handle, starting at the bottom of the tomato (opposite to where the cross is), peel off the skins. They should release very easily, although you’ll always find the odd stubborn one.
  • Once peeled, chop tomatoes back into a large pan. As you chop, it’s worth trying to get some of the seeds out, although you don’t want to waste the fruit.
  • You don’t need to add any water or any seasonings or onion or garlic at this stage. This can all happen when you use them in your cooking.
  • Lastly add the juice of a lemon to increase acidity. When foods are bottled, the safety of the food depends primarily on the amount of acid in the jars. The amount of acid in tomatoes is highest in unripe fruit and reaches the lowest point as the fruit reaches maturity. Research now tells us that tomatoes are not consistently high in acid and it’s recommended that acid be added to all bottled tomatoes.
  • Boil for 5 minutes. In the meantime heat up your water bath to 100 degrees or lay a tea towel in a large preserving pot and get water boiling in it.
  • Fill sterilised jars with tomatoes using a funnel up to 1 cm from the top to allow for expansion in the water bath. If you get tomatoes on the rim of the jar, wipe it dry with a paper towel, otherwise it may not seal properly.
  • Pop sterilised lids on as you go.
  • Then transfer the jars to the water bath, making sure they’re fully submerged in the water, put the lid on the water bath and leave for 20 minutes.
  • When you bring the jars out, you’ll notice within around 20 minutes that the lids all suck down. This is the sign that you’ve successfully preserved your tomatoes. If they don’t suck down, you should use the tomatoes in your cooking this week.


Camera: Hugh Williams
Editor: Thomas Asche