Dried lime

• loomi

  Arabic

• limu omani

  Persian

  Named for Oman, where much of the supply has historically come from.

Intensely sour with a fermented, earthy depth and a real bitterness from the pith and seeds. The sourness is cleaner than tamarind, the bitterness more pronounced than sumac, and the musty note is unique among the souring agents here.

Sour, musty and faintly fermented, with citrus oil somewhere underneath. It smells more like a cellar than a fruit bowl, which is disconcerting the first time and is exactly right.

Tan to deep brown outside for the white type, near-black for the black. Inside, the flesh is dark, dry and papery. A good one is startlingly light for its size and rattles when shaken.

Hard, hollow and brittle, crushing to a papery shell and a dry dark pulp. Whole limes are pierced and simmered, then discarded or eaten around; ground, it makes a coarse dark powder.

• Citric acid — The sourness, concentrated by the loss of nearly all the water in the fruit.
• Limonene and citrus terpenes — Much reduced by the long drying, which is why dried lime smells so little like fresh lime.
• Limonin and related limonoids — From the pith and seeds, and the source of the characteristic bitterness. Because the fruit is dried whole, nothing removes them.

Pierce it and put it in whole. Two or three holes with a knife or skewer let the sourness out gradually over a long simmer, which is what the ingredient is for — one or two limes season a stew for four, and they go in near the start. The one thing to watch is bitterness: the fruit is dried whole with its pith and seeds, and left in a pot for hours it will eventually make the dish bitter rather than sour. If that starts to happen, take them out; the sourness is already in the liquid. Ground dried lime is a different tool for a different job — a quarter teaspoon in a rub or a spice mix, added late — and using it at whole-lime quantities produces something harshly bitter. Do not substitute fresh lime: the drying is what makes this taste of anything more than acid.

Persian khoresh above all — ghormeh sabzi in particular — and Iraqi and Gulf stews, rice dishes, fish, and lentil and bean dishes. Ground, it goes into regional spice mixes and rubs, and steeped it makes a sour tea. It works with lamb, beef, chicken, white fish, lentils, kidney beans, spinach, herbs, rice and dried fruit, and alongside turmeric, cinnamon, black pepper, cardamom and saffron.

• boiling — The standard use. Whole limes are pierced and simmered in a stew or soup for the length of the cooking, releasing sourness gradually. Left too long they turn the dish bitter, which is the commonest error.
• grinding — Ground to a dark powder for spice mixes and rubs. Much more immediate and much more bitter than the whole fruit, so a small fraction of the whole-fruit quantity is right.
• infusing — Steeped in hot water to make the sour tea drunk across the Gulf, and used the same way to sour a dish without simmering the fruit in it.
• toasting — Not toasted. There is nothing to gain and the papery shell scorches.

Pick one up. A good dried lime is startlingly light for its size, hard, and rattles faintly when shaken because the inside has dried away from the shell. One that feels heavy or gives under the thumb has taken up moisture and is on its way to spoiling — and that judgement is available through the packaging, which is unusual.

• Soft or pliable rather than hard and light
• Visible mould, particularly around the stem end
• A flat sourness with none of the musty depth

• Moisture uptake, softening the fruit and eventually allowing mould
• Loss of the remaining citrus volatiles, leaving sourness and mustiness alone
• Caking of the ground form

Whole, and buy more than you think you need because they keep for years and cost very little. Whole limes give a slow sourness that builds through a stew with the bitterness held in check, which is the behaviour Persian and Iraqi cooking is built around; ground powder delivers everything at once, bitterness included, and is worth having only for rubs and spice mixes. Grind your own when you want it. Middle Eastern grocers sell them by the bag for a fraction of what a small supermarket jar costs, and the weight test works through the packaging.

• Light for its size, hard, and rattling faintly when shaken — the single best indicator and one you can apply through the bag.
• Intact rather than cracked, since a cracked lime has lost its aroma.
• No softness and no mould around the stem end.
• Whole rather than ground, and choose the type the dish wants — black for meat stews, white or tan for lighter dishes.

Traded by colour type, size and soundness rather than by any published grade. The black and white distinction is a processing choice rather than a quality ranking, and neither is better than the other in general.

Rutaceae

A thorny citrus shrub or small tree of the tropics and subtropics, bearing small thin-skinned green fruit. The spice is a processing product rather than a distinct cultivar.

The Gulf, and Oman in particular, where the technique originated and from which the trade name loomi omani comes. The limes themselves are often grown elsewhere and processed regionally.

• Oman — origin. The origin of the technique and of the most widely used trade name.
• Iran — major producer. Where limoo omani is a kitchen staple and much of the supply is processed.
• Iraq — notable producer
• India — notable producer. A source of the fresh limes rather than of the finished spice.

Limes picked ripe or nearly so, then processed whole. Fruit quality matters less than for fresh use, since the drying dominates the result.

1. Boiling in brine — Whole limes boiled briefly in salted water.Why: Kills surface organisms, softens the skin and begins the internal changes that produce the fermented character.
2. Sun drying — Laid out in full sun for two to four weeks until completely dry, hard and light enough to rattle.Why: The long slow drying is where the flavour develops. A quickly dried lime is merely sour.
3. Darkening — Limes intended as black are dried longer, and internal browning turns the flesh from tan to near-black.Why: A deliberate stage rather than an accident of age, and the difference between the two commercial types.
4. Grading — Sorted by size, colour and soundness. A lime that has cracked in drying loses aroma and is downgraded.

Traded by colour type, size and soundness. There is no published consumer grade and no declared acidity figure.

Little documented. The practical quality risks are cracked or mouldy fruit and limes dried too quickly, both of which are visible or detectable by weight and smell.

Hot and arid for the drying, which is done in full sun over weeks. The climate is as much a part of the product as the fruit.

A preservation technique that became a flavour. Drying limes whole allowed a perishable sour fruit to be kept and traded across the Gulf, and the fermented character the process produces turned out to be worth having in its own right — which is why the spice survived refrigeration.

A regional trade centred on the Gulf, moving between Oman, Iran and Iraq and outward to diaspora communities. Small by international standards and central where it is used.

Documented traditional use as a digestive across Gulf and Persian traditions, with the tea drunk for that reason as much as for refreshment. Recorded as documented tradition. SpiceHQ holds no clinical source and makes no health claim.