Asparagus are long, slender vegetables that grow as shoots in spring and early summer. The straight, firm stalks, which range from pencil thin to as thick as your thumb, are prized for their delicate flavour; the "tender tips" have a particularly delicate flavour and texture. The most common variety is green and sometimes tinged with purple at the bud. White and purple stalk varieties are also available. Look for asparagus with crisp, straight stalks and tight buds. Wrap in damp paper towels and refrigerate in a plastic bag for up to 4 days. Trim the stalks before using. Cut or snap off the tough ends and discard. If desired, peel the bottom third or half of each stalk with a vegetable peeler for a more tender texture.