Sour cream

For various reasons, sour cream is an excellent replacement for crème fraîche. For one thing, most people already have a container of crème fraîche in their fridge, which may be a lifesaver if you're halfway through cooking and find you're out of crème fraîche. Second, it's easy to find, so even if you end up doing your food shopping at a bodega or a petrol station, you'll be OK. Finally, its trademark sour flavor may be used in many dishes in place of crème fraîche.

Having said that, there are some significant variations to be aware of. The most essential thing to remember is that sour cream contains less fat than crème fraîche and is more prone to curdling when heated. This implies that, whereas crème fraîche can be added to a soup while it cooks, sour cream should only be used for topping. Nobody likes curdled sour cream in their sour cream. Another thing to keep in mind is that, while crème fraîche has a somewhat tangy flavor, sour cream is quite acidic.