If you don’t have sour cream on hand when a recipe calls for it, or if you’d prefer to use Greek yogurt instead, good news: You can easily substitute Greek yogurt for sour cream. Just follow a few rules of thumb, say Milk Street Radio hosts Sara Moulton and Christopher Kimball, responding to a caller who poses the question on air.

You can make the switch if you’re subbing Greek yogurt into a soup that contains no starch and you’re stirring it in at the end. But in this case, be careful not to boil the soup, Moulton warns, otherwise the yogurt (and the sour cream too, for that matter), will curdle. (Try this swap as this finishing touch in our Ancho Chili Soup, for example.)

If you do intend to boil the soup, make sure it contains some starch—flour, potatoes or otherwise.

The substitute works in baking, too, but use whole fat Greek yogurt, the hosts agree. That’s because you’ll need the butterfat. If the recipe calls for just a ¼ cup of sour cream, it doesn’t matter as much whether you use full or nonfat yogurt. But any more (as in our Stovetop Chocolate Cake), and you should definitely use full fat.

And if you ask Kimball, he’ll tell you how he really feels:

“I would take all the nonfat yogurt and put it on a large boat and sink it somewhere in the middle of the Atlantic. Nonfat yogurt is like spackle.”

See here for more clever ways to cook with yogurt, from spreading it under eggs to using it in place of whipped cream.

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