Ingredient

Tahini

Tahini is ground sesame seeds and nothing else. Its one genuinely surprising behaviour is that adding water makes it seize into a stiff paste before, with more water, it suddenly loosens into a smooth sauce — and people give up at exactly the wrong moment.

The seizing, and why to keep going

Tahini is an oil-rich paste with very little water in it. Add a small amount of water and it disperses into the oil, and the ground sesame particles clump around it — so the whole thing thickens dramatically and looks curdled and ruined.

Keep adding water and whisking, and the system flips: there is now enough water to become the continuous phase, and the paste suddenly slackens into a smooth, pale, pourable sauce. It happens quite abruptly.

So when tahini seizes, the answer is more water, not less, and certainly not more oil. Add it a spoonful at a time and whisk, and it will come good. Adding lemon juice at the same time is normal and behaves the same way.

A basic tahini sauce

1. Put tahini in a bowl with a crushed garlic clove and a good pinch of salt.
2. Add lemon juice and whisk. It will stiffen alarmingly.
3. Now add cold water a tablespoon at a time, whisking hard between each.
4. It will thicken further, then loosen, then go pale and smooth. Keep going past the stiff stage.
5. Stop when it is the consistency you want — pourable for drizzling, thicker for a dip.
6. Taste and adjust: more lemon, more salt, more water. It nearly always wants more of all three than you first think.

What to use it for

• Hummus, where it is a third of the flavour and most recipes use too little. See hummus.
• Drizzled over roasted vegetables — cauliflower, aubergine, squash, carrots.
• As a dressing for salads and grain bowls, thinned with water and lemon.
• With grilled meat and falafel, plain or with herbs blended in.
• In baking — tahini and chocolate is an excellent combination, and it works in cookies, brownies and swirled through cakes.
• In dressings generally, where it does what mustard does — emulsifies and adds body.

Buying and storing

• Look for a runny, pourable tahini with a nutty smell. Middle Eastern brands are usually far better than supermarket own-label.
• It should taste nutty and only faintly bitter. Harshly bitter tahini is made from unhulled or over-roasted seeds and will spoil anything you put it in.
• It separates in the jar. This is normal — the oil rises. Stir it back in thoroughly, which is easier if you turn the jar upside down for a day first.
• Store it in a cool cupboard, or the fridge once opened if you use it slowly. Cold tahini is very stiff and needs warming.
• It keeps for months. Like any high-oil product it eventually goes rancid, which smells sharp and paint-like.

Common questions