Preserving dried tomatoes in olive oil

Safely preserve the rich, tangy flavour of summer tomatoes by storing them in olive oil.

Who doesn’t love using sun-dried tomatoes in their cooking! The intense flavour and chewy texture add a unique depth to a dish. Although they are associated with Italian cuisine, dried tomatoes in oil are versatile and can be used in cuisines from all over the world. From pasta sauces to antipasto platters, sandwiches to salads, explore the creative culinary possibilities with these rich and tangy gems that you’ve made at home.

Historically, the drying was done out in the Italian sunshine, but nowadays, we can recreate the process in a food dehydrator and get the job done in any climate. If you are new to dehydrating tomatoes, start by reading, ‘Best practise, drying tomatoes in a food dehydrator’.

Dried tomatoes are so much easier to use when they are infused in oil. Although tasty straight up, dried tomatoes are extremely hard and leathery and to use them, they must be rehydrated. Infused in olive oil, you can cut them up and use them immediately, without needing to rehydrate in water first. Apart from convenience, the concentrated flavour of tomatoes is enhanced by the herbal oil infusion.

FOOD SAFETY PRECAUTION

Historically, the function of oil is to prevent oxidation, it is not a preservative. While storing tomatoes in oil is a time-honoured practise there is a potential food safety risk unless certain basic precautions are taken. Fortunately, when tomatoes are correctly dehydrated, the natural acid components become so concentrated that the risk of food poisoning is eliminated. Bottom line - the tomatoes must be fully dried and only dried herbs, dried spices and dried garlic can be used. Nothing fresh can be added to the jar.

VINEGAR IS A PRESERVATIVE

We immerse the dried tomatoes in boiling water and vinegar to acidify and preserve them before storing in oil. The brief dip rehydrates just enough for the tomatoes to absorb the vinegar more easily. As a bonus, this step also improves the texture. If you stored dehydrated tomatoes in olive oil (without rehydrating slightly first) they’d remain tough and chewy.

This step sounds counter initiative and you may wonder why you can’t simply dehydrate the tomatoes partially or at least for less time. For several factors, tomatoes don’t dehydrate evenly. For example, some of our segments dried in 10 hours while others took twice that time. To eliminate any opportunity for bacteria to thrive under the oil, all the tomatoes must be completely dried. 

INFUSION

To infuse the oil with additional flavour, you can add various dried herbs, spices, and aromatics. Popular options include dried basil, oregano, thyme, rosemary, bay leaves, chopped garlic, chilli flakes, pepper corns, or citrus.

Heating the olive oil slightly will help to soften the tomatoes, draw out the flavour, and move the seasoning deeper into the tomatoes.

You will need quite a bit of oil, but you will be able to use it in cooking when you use up the tomatoes. The left over, rich, and fruity tomato oil is delicious used as a flavourful drizzle on crusty bread, in salad dressing, dips, and so much more.

STORAGE & SHELF LIFE

Once the jar is packed and filled with oil, leave it for several weeks in a cool and dark place for the flavours to develop. Dried tomatoes in oil have a long shelf life, (up to a year or more), as long as there is no cross-contamination. Remove tomatoes from the jar as needed, keeping the jar sealed in between. Tomatoes that are exposed to air will mold over time, so each time you open the jar, make sure to submerge the remaining tomatoes under the oil or add extra olive oil if you need to.

WATCH HOW HERE

This recipe makes 2 small jars. Increase the quantity of fresh tomatoes for more jars.   

INGREDIENTS

2 kg fresh Roma tomatoes
1 litre water
½ cup white vinegar
2 teaspoons dried herbs (we used a mix of basil, oregano, and thyme - see notes for options)
8 cloves of garlic, peeled and sliced, (optional)
2 cups (approx.) good quality extra virgin olive oil

METHOD

Dehydrating Tomatoes
1.   Wash and dry the tomatoes. Cut them in half or quarters, depending on your preference or the size of your tomatoes.
2.   Place the tomatoes cut side up on the trays. Tomatoes shrink to half the size, so it is not necessary to leave too much space between.
3.   If you would like to add garlic to your oil infusion, place sliced garlic cloves onto a dehydrator tray lined with a silicone mesh sheet and dehydrate with the tomatoes. (store-bought dried garlic may also be used)

4.   Set the dehydrator to 60°C (140°F) and the time to 8 hours to check in. It may take up to 20 hours to fully dry the tomatoes. The dehydrating time will vary depending on the size and type of tomatoes you are using, and the humidity in the air.
5.  A completely dehydrated tomato should be dry and leathery with no moisture coming out when you squeeze them with your fingers. If you drop them on the bench, they should make a clink sound.
6.   Remove the dried tomatoes and store in an airtight glass container. Leave the moist pieces on for longer. Continue checking in every 4 hours until they are all dehydrated.
7.   When all the tomatoes are completely dry you are ready to create the oil infusion. You can do this right away or leave the dried tomatoes in an airtight container for days or weeks. They will not spoil.

Oil Infusion

8.   Start by sterilising the jars and lids by boiling for 5 minutes. Take out the jars with tongs and place upside-down on a wire rack to drain and dry.
9.   Add the water and vinegar to a medium sized saucepan and bring to a steady boil. Add half of the dehydrated tomatoes and boil for 2 minutes.

10.  Remove the tomatoes with a slotted spoon and place in a single layer on clean kitchen towel. Lay another clean towel over the top and gently press down to blot them dry. Repeat the process with the remaining dehydrated tomatoes. The dehydrated tomatoes will now be softer and more pliable.
11.  Prepare the dried herbs, garlic etc that you are choosing to put into your oil infusion. (Nothing fresh can be added to the jar.) 

12.  Start packing dried tomatoes into the sterilised jars. Working in layers, sprinkle in the herbs and garlic (or aromatics of your choice) as you fill the jars.
13.  Gently heat the oil in a small saucepan to approx. 100F/38C.
14.  Pour the olive oil over the tomatoes, making sure they are completely submerged. Press down on the tomatoes to release pockets of air and ensure they are completely submerged. Pop on a lid and that’s it, your own dehydrated tomatoes in oil are ready to preserve. 
15.  As you use the tomatoes, just be sure the remaining tomatoes are fully covered before storing back on the shelf (add more oil if needed).

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