<p>Springtime delivers a bounty of tender green asparagus spears to the farmers market. Not only are they delicious harbingers of the new season, but green asparagus are a powerhouse of nutrients: naturally rich in potassium, folate and vitamins A, C, E and K —and they are low in calories to boot.</p><p>When choosing asparagus, select rigid (not floppy) stalks with dark, firm tips. To store, trim the ends and refrigerate upright in an inch of water to maintain freshness.