Yoghurt soup is one of the less-known applications of yoghurt in the West, but it’s a staple across a wide arc of the world – from the cold cucumber soups of Persia to the warm, lamb-filled versions of Turkey and the tangy, grain-based soups of Bulgaria. It’s one of the most versatile and underrated things you can do with a tub of plain yoghurt, and once you’ve tried it, it’s difficult to see yoghurt as only a breakfast food.
The Challenge: Preventing Curdling
The main technical challenge with warm yoghurt soup is preventing the yoghurt from curdling when heated. Yoghurt destabilises and separates above about 85°C, producing a grainy, unpleasant texture. There are two solutions: either keep it cold (no problem), or stabilise the yoghurt before heating. To stabilise: whisk an egg and a tablespoon of cornflour into the yoghurt before adding it to warm soup. This allows it to be heated gently without breaking. Add the stabilised yoghurt off the heat and warm very gently, stirring constantly – do not boil.
Persian Abdoogh Khiar (Cold Yoghurt Soup)
Combine: 500g full-fat yoghurt, 1 cup cold water or sparkling water, 1 Lebanese cucumber (diced small), a handful of raisins, a handful of walnuts (roughly chopped), a handful of fresh herbs (mint, dill, and chives all work well), salt to taste. Mix everything together and serve immediately, or refrigerate for up to 2 hours. This is essentially a drinkable yoghurt with substantial garnishes – deeply refreshing in summer and a beautiful starter. Some versions add dried rose petals, which look striking and add a subtle floral note.
Turkish Yayla Corbasi (Warm Yoghurt and Rice Soup)
Bring 4 cups of good chicken stock to a gentle simmer. Cook half a cup of rice in the stock until just tender (about 15 minutes). Meanwhile, stabilise 500g of yoghurt: whisk in 1 egg and 1 tablespoon cornflour until smooth. Add a ladleful of the warm stock to the yoghurt slowly, whisking constantly (tempering), then pour the yoghurt mixture into the soup pot, stirring. Warm very gently – do not boil. Season with salt. For the finishing butter: melt 2 tablespoons of butter in a small pan, add 1 teaspoon dried mint and a pinch of paprika, and pour over the soup. The butter finish is essential – it adds richness and the mint fragrance transforms the dish.
Quick Weeknight Yoghurt Soup
For something fast: heat a can of chickpeas (drained) in 3 cups of vegetable stock with a teaspoon of cumin and half a teaspoon of turmeric. Stabilise 300g yoghurt as above and add off the heat. Finish with a handful of fresh spinach (it wilts from the heat of the soup), a squeeze of lemon, and salt. Ready in 15 minutes. The yoghurt adds creaminess and tang that makes this taste more considered than the ingredient list suggests.
Stabilising Without Egg
The egg-and-cornflour method gives the silkiest, most stable result, but if you would rather keep the soup vegetarian or eggless, you can stabilise with cornflour alone. Whisk a tablespoon of cornflour into the yoghurt with a splash of cold water until smooth, then temper and warm it gently as usual. It is slightly less foolproof than the egg version, so keep the heat low and stir the whole time. Either way the golden rule is the same, never let yoghurt soup boil.
Troubleshooting
It curdled and went grainy. The yoghurt got too hot, or went in without stabilising. Once it has split there is no full fix, though a quick blitz with a stick blender will smooth it out in a pinch. Next time, stabilise, temper with a ladle of warm stock first, and keep it below a simmer.
It’s too thick. Loosen it with a little more warm stock or water until it pours the way you like.
It’s too tangy. A very sour yoghurt can dominate. Balance it with a little more stock, a knob of butter, or a pinch of sugar, and make sure the salt is right.
Serving and Common Questions
Can I make it ahead? The cold versions are happy made a couple of hours ahead and kept chilled. The warm ones are best eaten fresh, and if you do reheat them, do it very gently over low heat, stirring, and never let them boil or they can split.
Can I freeze it? Yoghurt soups do not freeze well, as they tend to separate on thawing. These are quick enough to make fresh that it is not worth it.
Do I have to use full-fat yoghurt? Full-fat is the most stable and the richest. Low-fat works in the cold soups, but for the warm ones the extra fat in full-fat yoghurt helps it hold together when heated.
