Wild arugula ups the ante. It's not truly wild, of course, but a domesticated variety grown from seeds imported from Italy. Still, that "wild" tag could refer to its flavor. Its frilly leaves are both sweeter and more pungent and complex than regular arugula. The stems are a little tougher, too, but in a good way -- they promise snap in a salad and even allow the leaves to be cooked briefly without turning to mush.
How to choose: Look for arugula that is firm with no signs of wilting or discoloration. The stems may be wiry and a little tough, but that's part of the charm.
How to store: Store arugula in the refrigerator in a tightly sealed plastic bag. It'll last three or four days.
How to prepare: Toss the arugula with good olive oil and lemon juice. Season it with salt and a very little bit of black pepper. Use a vegetable peeler to shave shards of Parmigiano-Reggiano over the top.