Roasted & charred
Semi-Dried Tomatoes
Tomates semi-séchées · Fresh ripe tomatoes, halved, lightly salted, and slowly dehydrated at low temperature until 50–70% of their moisture is removed, yielding a pliable, intensely flavored product with concentrated sugars, acids, and carotenoids. Distinct from fully dried (crisp) or sun-dried (often stored in oil) variants.
The formula
Tomatoes : Salt = 100 : 2 by weight (raw); yield 1 kg fresh → 300–500 g semi-dried (50–70% moisture loss)
Salt draws initial moisture via osmosis, then low-heat evaporation (110–150 °C oven / 55–65 °C dehydrator) completes drying over 2–6 hours. The critical endpoint is texture — leathery and pliable, not brittle. For oil preservation: 100 g semi-dried tomatoes : 80–100 mL extra-virgin olive oil as submersion medium.
Identity
- Ripe, low-moisture tomato variety (Roma, San Marzano, plum) — not beefsteak or heirloom slicers
- Partial dehydration: 50–70% moisture removed, resulting in leathery but flexible texture, not crisp or brittle
- Light salt cure (2% by weight) applied to cut face before drying — draws liquid, seasons interior, inhibits early microbial growth
- No added sugar, acid, or preservative — flavor comes purely from concentration of tomato's own sugars and acids
- Stored submerged in olive oil with aromatics (garlic, thyme, basil) or packed dry in airtight container
Ingredients
| Base | Roma, San Marzano, or Italian plum tomatoes (ripe, firm, low moisture) | Use 500 g–1 kg. Avoid watery varieties; low water content is essential for successful semi-drying. |
| Seasoning | Fine sea salt | 2% of tomato weight (e.g., 10 g per 500 g tomatoes). Diamond Crystal or Maldon fine — avoid iodized table salt which can introduce metallic notes. |
| Fat | Extra-virgin olive oil (for storage submersion) | Optional but standard: 80–100 mL per 100 g finished product. Use a decent-quality oil — it becomes part of the component. |
| Aromatics | Garlic cloves, fresh thyme, bay leaf, or basil (for oil infusion) | Optional. Added to oil during the final minutes of cooling to infuse. Classic Provençal style includes a bruised garlic clove and a sprig of thyme per 100 g tomatoes. |
Method
- 1Preheat oven to 130–150 °C (conventional) or set dehydrator to 55–65 °C. Line a rimmed baking sheet with parchment. Core tomatoes and halve lengthwise.Low, steady heat drives moisture out slowly without caramelizing exterior before interior dries. Parchment prevents sticking. Dehydrator produces more even results with no risk of over-browning.
- 2Spread tomatoes cut-face up on baking sheet in a single layer, not overlapping. Season cut surface evenly with 2% salt by weight. Do not add oil at this stage.Salt draws osmotically from the tomato flesh, beginning moisture extraction and seasoning the interior as it evaporates. Oil here would create a barrier and prevent even drying.
- 3Place in oven or dehydrator. After 30 minutes, blot excess liquid pooled on baking sheet with paper towels. Rotate tray if browning unevenly.Blotting removes expelled water rather than letting it reabsorb into the flesh. Rotation ensures even air circulation and heat distribution, critical for consistent texture across the batch.
- 4Continue drying 2–5 hours total (oven) or 5–8 hours (dehydrator), until tomatoes are leathery and pliable — they should bend without snapping, and have lost 50–70% of original weight.The target moisture content for semi-dried tomatoes is 15–25% water (vs. ~94% in fresh). Weight loss is the most reliable indicator; visual/texture judgment is secondary. Over-drying makes them brittle and loses the rehydration quality.
- 5Cool to room temperature. If storing dry: pack tightly into a clean glass jar, pressing out air, and seal. If storing in oil: submerge fully in olive oil in a sterilized jar, adding aromatics. Refrigerate.Airtight dry storage works for short term (1–2 weeks). Oil submersion extends shelf life to 3–4 weeks refrigerated and creates a flavored oil byproduct (tomato-infused olive oil). Oxygen exposure causes rancidity and mold; oil creates an anaerobic seal.
Techniques that matter
Osmotic dehydration (salt cure)
Salt applied to cut surface creates a hypertonic environment, drawing intracellular moisture to the surface before bulk evaporation begins. Reduces initial drying time and improves seasoning penetration.
Low-temperature convection drying
110–150 °C oven or 55–65 °C dehydrator gently evaporates water without browning the surface too quickly. High heat would set color and create a crust before interior moisture escapes, leading to uneven semi-drying.
Anaerobic preservation (oil submersion)
Submerging in olive oil excludes oxygen, preventing aerobic mold growth (the primary spoilage risk for dried tomato products). The oil also extracts fat-soluble flavor compounds (carotenoids, volatiles) creating a dual-purpose flavored oil.
Variations & derivatives
Provençal Confit de TomatesProvence, France
Classic: San Marzano or heart-shaped tomatoes, halved, salted, dried 4–6 hours at 120 °C, then packed in herb-infused olive oil with a bruised garlic clove and sprig of rosemary. Often finished with a pinch of sugar to balance acidity.
Sun-Dried Tomato Paste (precursor)Southern Italy / California
Fully dried (not semi-dried) Roma tomatoes, rehydrated and blended to paste. Technically a downstream derivative, but semi-dried tomatoes are the intermediate product.
Tomates Secas (Brazilian)Brazil
Often sliced rather than halved, salted and sun-dried or oven-dried, then packed in soybean oil with bay leaves. The semi-dried stage is brief; they remain more moist than Italian versions.
Used in these dishes
Substitutions
- Fresh ripe Roma/plum tomatoes → Cherry tomatoes (halved, longer drying time) — Smaller water content per surface area means longer drying but acceptable. Result is sweeter and more prone to burning — monitor at 3 hours.
- Sea salt → Fleur de sel or Morton kosher — All work. Avoid iodized salt. Use weight measurement, not volume, for accuracy.
- Dehydrator → Oven at lowest setting (90–100 °C with door cracked) — Air circulation is critical; a wooden spoon in the oven door gap provides ~2 cm ventilation. Drying time increases by 30–50%.
- Olive oil submersion → Grapeseed or neutral oil — Functional for preservation but sacrifices the olive oil's flavor contribution. Not recommended for finished component quality.changes result
Troubleshooting
Tomatoes turn brown and brittle rather than leathery
Oven temperature too high (>160 °C) or tray placed too close to heat source — surface caramelization and Maillard browning occur before interior moisture escapes → Reduce oven to 120–130 °C, use middle rack, and check every 30 minutes. If browning occurs early, tent loosely with foil for the first hour to moderate heat exposure.
Mold appears on dry-stored tomatoes within 1 week
Insufficient moisture removal — final water content above 20%; or inadequate airtight sealing allowing humidity reabsorption → Return to oven at 120 °C for 15–30 minutes to drive off residual moisture, then cool completely before re-sealing. Use a vacuum seal or press out all air manually when packing.
Tomatoes in oil develop off smell within days
Oil not fully covering tomatoes (anaerobic seal broken) or container not refrigerated; also from using poor-quality oil with high free fatty acid content → Ensure tomatoes are fully submerged by 1 cm minimum. Use fresh, cold-pressed olive oil. Refrigerate after 24 hours at room temperature. If oil smells rancid, discard and replace.
Texture too wet and soft — not semi-dried
Insufficient drying time; tomatoes weighed before fully dried; or starting tomatoes were overripe and too watery to begin with → Extend drying time by 1–2 hours. Use a kitchen scale: if tomatoes haven't lost 50–70% of original weight, keep drying. Switch to Roma/plum type for future batches — they have 5–6% dry matter vs. 4% for beefsteak.