Actually very easy

Sun-dried tomatoes

The beliefDried tomatoes are assumed to need a facility, or at least a dehydrator.

The truthSun, salt and three days. The one real rule is to bring them in at night.

Twenty minutes of work, three days of drying

How to make it

What you need

3 kg ripe, meaty tomatoes — a paste variety is best
2 tablespoons of salt
A wire rack or clean cloth, and muslin

How the engine read this list (2 lines)

3000 g	Ripe, meaty tomatoes	tomato
36 g	Salt	salt

An empty weight means that line could not be turned into grams — either the amount is open ("to taste") or the ingredient has no record here. Neither enters the sum as zero; they do not enter it at all.

Halve the tomatoes and spoon out the seedy pulp: its water lengthens the drying and brings bitterness.
Lay them cut side up on a rack and scatter a little salt over them.
Cover them with muslin and put them in the sun. The muslin is for flies and does not shade them: direct sun is essential.
Bring them in every evening before sunset and put them out again in the morning. Dew can mould three days of work in one night.
After three days they should be leathery and pliable but not damp — squeezing should release nothing. Jar them dry, or store them under olive oil.

Why it works

Drying is the oldest way of preserving food, and its mechanism reduces to one idea: water activity. A fresh tomato sits at 0.99 — ideal for very nearly every microorganism. Drying takes it below 0.6, and under that threshold no bacterium, mould or yeast can work. Salt does two jobs: it speeds the water out by osmosis, and it lowers the water activity at the surface, shortening the risky window before drying finishes. That is also why they come in at night — dew returns to the surface exactly the water microbes need, and one careless night can mould three days of work. Cutting them in half and laying them cut side up is technique too: the water leaves by evaporating from the open face, not by falling.

The rough sum

3036 grams going in

540 kcal in total

100% of the mass has figures behind it. This is the sum of what GOES IN rather than of what comes out. Wherever something evaporates, drains or ferments the two differ: a kilo of milk is 150 g of cheese.

Diets it qualifies for

Gluten-free Vegan Vegetarian Lactose-free

Storage & shelf life

How long it keeps

Fully dried, in a jar: 1 year
Under olive oil, in the fridge: 6 months
Under olive oil, at room temperature: 1 month
Freezer: 1 year

Storing under oil carries a real risk worth naming: oil excludes oxygen, and an oxygen-free environment suits Clostridium botulinum. Vegetables kept under oil therefore need to be either acidified or refrigerated, and doing both is safe. Fully dried tomatoes in a dry jar never raise the question at all, because their water activity is already far too low. White crystals in the jar are usually salt rather than mould — but if you are unsure, smell it: mould smells of cellars.

When to bin it Fuzzy or coloured patches, a cellar smell, or oil that has clouded and started to bubble mean all of it goes. A domed lid on an oil-packed jar is taken just as seriously.

History

Where it comes from

Drying tomatoes happens all around the Mediterranean, but in Anatolia it belongs to a tradition of winter preparation: paste, tarhana, erişte and dried tomatoes are made in the same weeks on the same rooftops. What is interesting is that drying is not only storage but concentration — with the water gone, the tomato’s glutamate and sugar multiply, which is why a dried tomato carries far more umami than a fresh one. What restaurants now sell as concentrated flavour was known in the village simply as the winter store.

The knack

Without sun, the oven at 70 °C with the door ajar dries them in eight to ten hours. The result is a shade darker but technically the same.
Decide in advance whether they will be fully dried in a jar or left leathery under oil: half-dried tomatoes mould in a dry jar.
Before storing under oil, soak them five minutes in acidulated water and pat dry. Acid secures the surface; oil alone is no protection against botulism.

Preserves and syrups