If you've ever had a bagel with smoked salmon, you've most certainly had a caper. Capers are the buds of the caper plant, and are most commonly sold brined in a solution of vinegar and salt. They're savory, salty, and slightly bitter, and pair beautifally with salads, pastas, and fish. ; In today's What's This Food?!, we turned capers into a butter, perfect to use on fish and pasta.