OYSTERS ON THE HALF SHELL

OFAVORITE WAY TO SERVE OYSTERS IS ON THE half shell. This is the best way to showcase their intense and exotic flavors. Oysters may be cooked in a stew or stuffed and baked, but we find that these preparations diminish the traits we like best about oysters. Serving oysters on the half shell also allows you to appreciate the stunning differences in oyster varieties.

It's easy to become overwhelmed by oysters. As if they weren't challenging enough to open, there are so many kinds it's hard to figure out what to buy. Walk into a good seafood shop and you may find Gliddens from Maine, Wellfleets from Massachusetts, Chincoteagues from Virginia, and Kumamotos from the West Coast. What's the difference and which should you buy?

The first thing to know is that there are only five species of oysters seen in the United States (see figure 8). The three most important are the familiar Atlantic, grown all along the East and Gulf coasts; the European, grown in the Northwest and a few spots in the far Northeast; and the Pacific, grown all along the West Coast. In addition, there are Olympias, oysters the size of a half-dollar that are indigenous to the Northwest and rarely seen elsewhere, and the trendy Kumamotos, once considered a variety of Pacific oyster but recently declared a distinct species.

The problem for shoppers is that within each of the three most popular species there are myriad nicknames and place names: The Atlantic is not only called the Eastern but is casually referred to by many place names (such as Wellfleet and Chincoteague); the European is known as the "flat" and also—incorrectly—as the belon, a name that belongs to oysters from a small region in France; and the Pacific, which is also grown in Europe, not only has place names attached to it but is sometimes called a Portuguese ("Portugaise"), after a now-extinct species that once made up the majority of oysters grown in Europe.

All this nomenclature business would be fodder only for linguists if oysters did not taste so different from one and another. An oyster from the mainland-facing side of Martha's Vineyard and one from the Atlantic side, for example, taste as different as two good but distinct bottles of Napa Valley Merlot. In fact, oysters are quite a bit like wine: You have the species, which corresponds to the grape variety, and the specific oysters from each location, which correspond to individual wines. Climate, water quality, and the age and condition of the growing beds are among the factors that affect the taste of an individual oyster.

Nevertheless, just as all Merlots have some things in common, so do all oysters from a particular species. To describe the major attributes of each species, we had more than a dozen people taste 13 kinds of oysters from all over the country. Here are the general conclusions from our panel's tasting notes.

ATLANTIC OYSTERS Crisp and briny, with a fresh, cold flavor of salt, and lightly fishy. Easy to like and not complex. Range in size from 2 inches to nearly 6 when grown in warm southern waters. We preferred crisp, brinier oysters (Wellfleets, Blue Points, etc.) from cold northern waters. Southern oysters (Chincoteagues, Apalachicholas, etc.) were softer, flabbier, and not nearly as briny.

PACIFIC OYSTERS Rarely salty but very complex tasting and often fruity. (Many tasters compared the flavor with cucumber or watermelon.) Sometimes sweet or even muddy. Our tasters preferred them sweet rather than muddy tasting. Usually 3 to 4 inches long.

EUROPEAN OR FLAT OYSTERS Very challenging and off-putting to oyster novices. When good, they start out tasting crisp and briny (like an Atlantic), but the finish is strong and metallic—something many oyster connoisseurs love. These oysters are round and measure about 5 inches in diameter.

KUMAMOTOS Very appealing because they combine the complexity of the Pacific oyster with more sweetness and less muddiness. Can be briny in the same way as good Atlantics. Because they're fairly small, they can be eaten in one bite.

OLYMPIAS Very hard to find outside of the Northwest. If you do find them, they are usually briny and metallic, much like flats. Very small.

In addition to considering species, pay close attention to freshness and season when shopping. The best oyster is the freshest. Older oysters are drier, flabbier, and less flavorful. Merchants are required by law to keep the tags that come with each container of oysters. The tag shows the place of origin and date of harvest. A reputable fishmonger can tell you exactly where and when an oyster was harvested. Any oysters more than a few days old should not be purchased.

Season is also key. The old adage about not eating oysters during months that don't contain the letter R is not as important as it used to be, when people spurned oysters in the summer because they died more quickly out of the water. But many oysters do spawn in the months without an R—May, June, July, and August—and spawning makes the meat mushy and less appetizing.