The only thing to fear in a yoghurt soup is the yoghurt splitting. The cause is thermal shock: cold yoghurt meeting boiling liquid makes its protein clump. There are two defences, binding the yoghurt with flour and warming it a spoonful of hot liquid at a time. Do both and the soup will take a boil and stay smooth.
Ingredients
For the soup
For the egg-lemon thickening
For the top
Method
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Toast the orzo
Toast the orzo in butter for 3 minutes, until the smell comes up.
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Cook it
Add the water and salt, bring to the boil and cook for 12 minutes until the orzo is tender.
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Make the tempering mixture
Whisk the yoghurt, egg yolk and flour until smooth.
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Warm it
Add ladles of hot liquid from the pan a little at a time, stirring. At least six ladles; the mixture should feel warm to the hand.
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Combine
Pour the warmed mixture into the pan in a thin stream, stirring as you go.
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Bring to the boil
Cook over a low heat for 8 minutes, stirring constantly in one direction. Past this point it will not split.
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Burn the butter
Heat the mint and pepper flakes in butter for 30 seconds and drizzle over the soup.
Tips
- Do not use yoghurt straight from the fridge; yoghurt at room temperature splits far less.
- Stir in one direction once the mixture is in. Changing direction breaks the bond.
- The flour looks skippable and is not; it is what makes the yoghurt able to take a boil.
- If it does split, take it off the heat and blend it; the look recovers to a large extent.
Nutrition
Values are per serving and approximate.