In the culinary arts, capers are a condiment, usually pickled, that are made from the immature flower buds of the caper bush (Capparis spinosa), which grows in Mediterranean regions.
Capers are used in a number of Italian recipes such as chicken piccata, veal piccata and pasta puttanesca. Sometimes capers are cured by salting rather than pickling. Cooking with capers is a matter of balancing their tangy, briny, pickly flavor against some sort of smooth, buttery or velvety flavors and textures.
They're also widely used in sauce making, in salads, as a condiment or as a flavorful garnish. Capers are frequently used in conjunction with lemons. They pair well with salmon, especially smoked salmon.
Of the various types of capers that are available, the most desirable are the non-pareils (sometimes referred to as "nonesuch"), which are small (around 7mm or barely more than 1/4 inch in diameter) and firm, and supposedly expensive, although I've never paid more than $4 for a jar of them.
The bigger ones can be acidic, so use them sparingly and be sure to balance out the flavors. If you're using them in a chicken salad or egg salad, you'd want to chop them up a bit.
Note that capers are not the same thing as caperberries. While capers are the immature flower buds of the bush, caperberries are the fruit the bush produces once the buds have flowered and then been fertilized.
Caperberries are harvested with their stems attached, and they are cured in vinegar just like capers.
You can eat them whole, including the seeds, but remove the stems first.
When using either capers or caperberries, it's a good idea to rinse them first, so that the hit of vinegar doesn't overpower the caper's unique flavor.
Similarly, when cooking with capers, it's best to add them near the end of cooking rather than simmering them (for instance, in a tomato sauce), because they can become bitter if cooked too long.
Capers substitute: Because capers have such a strong briny taste, you could try using finely diced green olives instead.
Another use for capers is as a pizza topping. I'd personally make a pizza topped with mozzarella cheese, sliced red onions and capers.
Capers are also the traditional garnish for beef carpaccio. They can also go in chicken salad, pasta salad or potato salad, on top of deviled eggs, or in the classic Nicoise salad. Capers and caperberries can even go in a martini cocktail in place of the olive. And speaking of cocktails, caperberries make a terrific garnish for a Bloody Mary.