Roast Chicken Tartines with Arugula and Capers

Capers are actually the preserved flower buds of a prickly bush that grows all over the Mediterranean. (The plant’s fruit, usually known as a caper berry, has the same color as a caper once preserved but is much larger and meatier, with a pronounced stem.) We prefer salt-packed capers over their brined cousins because they’re more tender and flavorful—just make sure to rinse them well before using.