Cumin

Whole and ground go in at different times

• Whole cumin goes into the oil at the start. About thirty seconds and it crackles and opens up. In Indian cooking this is often the very first move.
• Ground cumin goes in mid-cooking, for 20-30 seconds only. Its surface area is large, it catches fast, and burnt cumin leaves bitterness through the whole dish.

Add both at the same moment and one is underdeveloped while the other burns (blooming spices). The filling for samosa starting with whole cumin and adding ground spices later is this principle in order.

Toasting makes it a different spice

Cumin is unusually transformed by toasting. Raw it is sharp and slightly earthy; two minutes in a dry pan brings out a sweet, nutty aroma.

Buying it whole and toasting and grinding it as needed gives something noticeably different from shop-bought ground. It is extra work, but with this spice the difference shows.

It is easily confused with caraway

They look alike, and European languages often blur the names — German Kümmel means caraway. Their aromas are unrelated: caraway leans anise-sweet, so substituting moves a dish towards Northern and Eastern Europe.

Black cumin (shahi jeera) is another thing again — finer and more delicate, used in dishes like biryani, and not to be measured like ordinary cumin.

The same spice sits in different places

• India: the base of curry aroma — chana masala, vindaloo, biryani.
• The Middle East: the signature scent of hummus and falafel.
• North Africa: central to the spice blend of a tagine.
• Mexico: half of what chilli and taco seasoning smells of.

Because it is so widely spread, cumin in the air does not mean Indian food. What it is used with is what fixes the nationality.

Storage

• Reckon on two years whole, six months ground.
• Sealed, in the dark. If rubbing some between your palms releases little scent, it is past it.
• Buying ground cumin in bulk is usually a false economy. Whole, ground in small amounts, works out cheaper by the time you have used it.

Substitutes

• There is no clean substitute, least of all in a dish where cumin is the centre of the aroma.
• If you must approximate: roughly two parts ground coriander to one of caraway.
• Do not reach for chilli powder. Commercial blends already contain cumin, which makes the quantities impossible to reason about.