How do I cook with yoghurt without it splitting?

Cultured yoghurt is milk whose casein proteins have already been brought close to the point where they clump. Heat pushes them over it, and they curdle into grains suspended in whey. Every technique for cooking with yoghurt is a way of holding those proteins apart while they get hot.

What you'll need

• Full-fat natural or Greek yoghurt
• Cornflour (optional)
• A whisk

Step by step

1. Start with full-fat yoghurt.Fat physically separates the protein molecules and buffers the heat. Low-fat and fat-free yoghurt split almost immediately in a hot pan, and no amount of technique fully compensates. Greek or Greek-style strained yoghurt is the most stable of the common types.
2. Bring it to room temperature first.Fridge-cold yoghurt hitting a hot pan is a thermal shock and the proteins seize. Twenty minutes on the counter, or a quick temper with hot liquid, removes most of the risk on its own.
3. Stabilise it with starch — the reliable method.Whisk one teaspoon of cornflour, or a tablespoon of plain flour, into 250g of yoghurt until completely smooth. The starch granules swell as they heat and physically get between the proteins. This is the standard method in Turkish, Greek and Persian cooking and it works completely.
4. Cook the stabilised yoghurt on its own first.Put the yoghurt and starch in a pan over low heat and bring it slowly to a bare simmer, stirring constantly in one direction. Once it has simmered for a couple of minutes it is set and will not split, and you can then add it to the dish or add the dish to it.
5. Temper if you are adding it to something hot.Take the pan off the heat. Stir a ladleful of the hot liquid into the yoghurt, then another, then pour that back into the pan. You are raising the yoghurt's temperature gradually rather than shocking it.
6. Keep it below a boil after it goes in.Even stabilised yoghurt is happier below simmering point once it is in a dish. A gentle heat, no lid rattling, and no reheating hard afterwards.
7. Add acid and salt carefully.Extra lemon juice or salt stirred straight into hot yoghurt encourages the proteins to clump. Season the dish rather than the yoghurt, and add lemon at the end off the heat.
8. Use it as a finish where you can.Not everything needs cooked yoghurt. A spoonful stirred in off the heat or dolloped on top gives you the tang and richness with none of the risk, and in many dishes it is the better answer.

Tips

• Strained or Greek yoghurt has less whey to release and is more forgiving than thin natural yoghurt in every hot application.
• A yoghurt sauce that will be served cold — raita, tzatziki, a yoghurt dressing — has none of these problems. The splitting question is entirely about heat.
• Whisk yoghurt smooth before it goes anywhere near a pan. Lumps of thick yoghurt heat unevenly and the outside of each lump curdles.
• In a marinade, yoghurt's mild acidity tenderises meat gently over hours without turning the surface mushy, and the milk proteins help browning. That use is unaffected by splitting.
• Coconut yoghurt and soya yoghurt split under heat in the same way and respond to the same cornflour treatment.

If it doesn't work

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