Salt-Dried Tomatoes

Salting and slow-drying turns watery tomatoes into deep, chewy, sun-dried-style halves — concentrated sweetness, savory tang, and a leathery bite that rehydrates into pasta, braises, and tapenade. Salt pre-treats the surface and the dehydrator finishes the job, but the safety line is a number: water activity.

Salt plus dry, as hurdles

Drying preserves by removing water until microbes cannot use what remains, and the governing figure is water activity (aw) — the fraction of water that is chemically available — not percent moisture. A light salting before drying lowers the starting aw, draws surface moisture, seasons the fruit, and shortens drying time. The two hurdles stack: salt binds some water, the dehydrator removes the rest. Where you land on the aw scale decides whether the result is shelf-stable, refrigerator-only, or oil-pack-with-caution.

Ingredients

Ingredient	1 Jar	1 Crock
Ripe plum / Roma tomatoes	~1,200 g (≈12 tomatoes)	~2,800 g (≈28 tomatoes)
Fine salt (non-iodized)	12 g (~1% pre-salt)	28 g
Optional: olive oil, herbs, garlic (for refrigerated oil pack)	as needed	as needed

Tomatoes shed most of their weight as water, so a big tray of fresh fruit collapses into a small jar of dried halves.

Yield: ~150–200 g dried halves per 1 Jar of fresh; ~350–450 g per 1 Crock. Storage life depends entirely on the finished aw (below).

Calculated values

Pre-salt: ~1% of fruit weight (12 g / 1,200 g) — light seasoning and surface draw, not a preserving cure. Use calc-dry-salt to scale.
Dehydrator temperature: 55–60 °C / 130–140 °F.
Drying time: ~6–12 hours depending on slice thickness and humidity.
Shelf-stable line (pathogens): aw below 0.85, measured on a meter.
Mold-free target: aw below 0.70 for the most robust pantry storage.

Readiness window

Done-when (texture cue): the halves are leathery and pliable — they bend and feel dry, with no beads of moisture when squeezed. This is a quality cue, not a safety reading.
Done-when (safety): for a room-temperature claim, cool a sample and read aw below 0.85 on a meter. Texture alone does not prove shelf stability.
Arrest / hold three ways:
- Drier (aw below 0.85), measured: condition for a week in a loosely lidded jar, shaking daily; any condensation means not dry enough. Then store airtight, cool, and dark.
- Chewy / not fully dried: treat as a fresh food — refrigerate at 2–4 °C and use within 1–2 weeks, or freeze.
- Oil pack: see the warning — refrigerate and use quickly; never store an oil pack at room temperature.

Method

Halve and seed

Wash the tomatoes, halve lengthwise, and scoop or squeeze out most of the seeds and gel so they dry faster and more evenly.

Salt lightly

Toss or sprinkle the halves with ~1% salt and let them sit cut-side up for 15–30 minutes. The salt draws surface water and seasons; blot off the beads that form.

Lay out for even drying

Arrange cut-side up on dehydrator trays in a single layer, not touching, so air moves around every piece. Uniform size matters — mixed thicknesses finish at different times.

Dry at a controlled temperature

Hold 55–60 °C for 6–12 hours. Too cool and the surface stays wet long enough to spoil; too hot and you case-harden a dry skin over a wet core. Rotate trays as needed.

Measure aw, do not guess

Cool a sample to room temperature and read aw. For unrefrigerated storage you must confirm below 0.85 (aim below 0.70 for long pantry life). No meter means no room-temperature claim.

Condition and store

Loosely jar and shake daily for a week to equalize residual moisture; discard any jar showing condensation. Then store airtight, cool, and dark — or refrigerate / freeze the not-fully-dried ones.

Variations

Herb-dusted: dust with dried oregano, thyme, or a little sugar before drying for a sweeter, sun-dried profile.
Tomato powder: dry hard (aim aw below 0.60) and blitz to a powder — an intense seasoning that keeps well dry.
Rehydrate-to-use: soak dried halves in warm water or stock for 20–30 minutes before adding to dishes.