Before we finish National Nutrition Month, it’s worth noting that the Centers for Disease Control puts out a nutrition score card for green vegetables. In the No. 1 slot: watercress. Not exactly a household veggie, watercress is a member of the mustard family. Its small, dark green leaves are packed with beta carotene, calcium, potassium and vitamin C. Slightly peppery, bitter and tangy, watercress adds zip to soups, salads and sandwiches. You can juice it into smoothies, use some as a burger topping or as a garnish like parsley. And like parsley, watercress should be used in moderation; a little goes a long way.