This unassuming bivalve has enjoyed a long and varied history. Early Romans extolled the oyster's aphrodisiac qualities, while American colonists begrudgingly depended on them to survive long, harsh winters. Few combinations are as simple and elegant as freshly shucked oysters and chilled Champagne. Lemon, lime, saffron, coconut milk, chilies, lemongrass, leeks, miso and cream all complement oysters. They also star in soups, stews and fillings.
Always buy oysters from reputable merchants who can vouch that they come from safe, clean, unpolluted waters. Fresh live oysters in the shell have a mild, sweet smell. Their shells should be closed tightly and feel heavy with water. Do not buy any oysters that remain open when touched. A strong fishy or ammonium odor indicates the oysters are no longer fresh, so pass them by. Any oysters intended for eating raw should be bought fresh and shucked within a few hours of serving. Do not buy shucked oysters for eating raw unless you know that the fishmonger shucked them specially for your order.
When buying containers of shucked oysters, check that the shellfish are plump and their liquor is clear, without a trace of milkiness. Some grocery stores and fish markets sell frozen shucked oysters. Also available are canned smoked oysters.
While oysters are spawning during the summer months, their flesh becomes soft, milky and less sweet. They are not toxic but simply taste unpleasant. In the United States and Europe, oysters are in season during the months that have the letter "r" in them—in other words, from September to April. Now, however, with sterile varieties cultivated, oysters are increasingly available all year long. A clear exception to the alphabet rule is the Kumamoto oyster, which spawns during the autumn months.
Spread live oysters in a large container and cover them with a damp cloth. If needed, keep them in the refrigerator for 1 to 2 days, making sure the cloth stays moist. They will die if submerged in tap water, stored on ice, or sealed in an airtight container. Cover shucked oysters in their own liquor and refrigerate them in an airtight container for no more than 2 days. Store cans of smoked oysters in a cool, dry place for up to 2 years. Keep frozen oysters for up to 3 to 4 months.
Since oysters are susceptible to water contaminants and "red tides" of poisonous plankton, be sure to read posted signs and check with local health or game agencies before collecting your own oysters.
Adapted from Williams-Sonoma Kitchen Companion: The A to Z Guide to Everyday Cooking, Equipment and Ingredients (Time-Life Books, 2000)