Oyster stew with leeks and prosciutto

We were wandering south along Tomales Bay a couple of months ago and stopped in for oysters at a little place called Marshall Store. I ordered up a dozen raw, and an icy Sierra Nevada. And then, just on a whim, I asked them to toss in another dozen oysters barbecued -- they’re a local specialty and I thought I at least ought to try them.

Barbecued oysters are not the kind of thing I usually order. I’ve always thought of cooked oysters as something you settle for -- what you eat only when the oysters are no longer of the first quality or when you have had so many raw ones you’re tired of them (and despite repeated attempts at reaching that limit, I have never even come close).

At Marshall Store, the raw oysters were magnificent, as expected; after all, we were eating them no more than five yards from the icy Northern California waters where they were grown. But what really amazed me was how great the barbecued oysters were. Freshly shucked, they were lightly brushed with garlic butter, quickly grilled and then finished with a squirt of house-made chipotle sauce.

The preparation was simple, but the result was beguilingly complex. All of the flavors were in balance: the garlic butter smoothing out the oysters’ sharp brininess and the chipotle sauce offering a hint of sweet smoke and fire.

Old prejudices die hard, but there is no arguing with delicious.

Curious, I started re-examining old oyster recipes. That’s where, as if to rub (sea) salt in my wounds, I came across this quote from James Beard: “Many gourmets, or so-called gourmets, tell you that to eat an oyster in any fashion except directly from the shell is to show ignorance of gastronomic tradition and the rules of good taste. This is nonsense.”

Back to the kitchen

Thoroughly chastened, I retired to my kitchen to explore. A couple of weeks and scores of cooked oysters later, I’ve learned that he’s right. Cooked oysters aren’t better than raw, but they are different -- and in a delicious way.

Cooking oysters changes their flavor and their texture. What was once aggressively briny, tasting like cold, clean seawater, is calmed, allowing the mollusks’ natural sweetness to shine through. The seductively slippery texture is firmed, turning from wet and wild to soothingly custardy.

The transformation is magical, whether you’re gently poaching the oysters in a rich tarragon-scented stew, or roasting them to be served with melting braised fennel or a sprightly chipotle butter.

But let’s be clear right from the start that when we talk about “cooking” oysters, we’re really talking about something closer to “warming” them. It takes only three or four minutes’ poaching and less than 10 minutes in the oven.

It’s really easy to tell when an oyster is done: You can see it plump and firm, and the small ring of muscle around the outside will gently curl. Perhaps it’s just my imagination, but it looks as if the oyster is smiling.

You should be smiling too. Though raw oysters are among nature’s most inconvenient foods -- even well-practiced oyster shuckers can run into problems opening them -- it’s pretty amazing what a little cooking can do.

The edible part of an oyster is basically one big muscle that is devoted to keeping the two halves of the shell closed. Warm an oyster in the shell, though, if only for five minutes or so, and the muscle relaxes. This makes opening it, if not quite a breeze, at least much easier. At this point it’s certainly not suited for the raw bar, but it’s still well short of fully cooked.

You can even do this in the microwave: 20 to 30 seconds on medium heat or “defrost” will do the trick. Don’t go any longer, though, or the shell will begin to give off a somewhat unpleasant smell.

Once the oysters are warmed, shuck them as you normally would: Wrap the oyster cup- side down in a dish towel to protect your hand. Probe the narrow hinge end with an oyster knife. When you find a spot where the knife can slip in a couple of inches, just give the blade a twist. It will pop the hinge, opening the oyster.

Use the sharp edge of the knife to separate the muscle from the shell, top and bottom, and you’re ready to go. It’s a good idea to work over a bowl, so you can catch any of the delicious liquid that leaks. Before you add it back to the dish, pour it through a strainer to remove any shell fragments.

Using jarred oysters

Jarred oysters, available at most good fish counters, can be handy, but in my experience they should be used with discretion. In the first place, I’ve found widely varying quality with different brands. The ones I’ve been happiest with have been from high-quality oyster growers such as Hama Hama (available at Mitsuwa markets) and Taylor Shellfish Farms (at Marukai stores or www.taylorshellfishfarms.com).

Be aware that the liquid in the jar is not oyster juice, but rather the clean water the oysters were rinsed with. It won’t add much to the dish.

Sizes vary and should be labeled on the jar. But even small jarred oysters may be bigger than you’d think. The Hama Hama “extra-smalls” I bought averaged 2 to 3 inches in length; the Taylor “mediums” were 4 to 5 -- practically knife-and-fork size. I figure a 10-ounce jar will yield the equivalent of about 24 of my hand-shucked oysters.

I found jarred oysters work best in stews and dishes like that. If you want to roast them, arrange the oysters and their accompaniments in small ramekins and cook them that way.

If you’re cooking oysters in liquid, you’ll probably want it to be cream or at least half-and-half. Oysters take to cream like ducks to water. There’s something about their flavor that seems to want a little richness to round it out. I’ve noticed the same thing with crab -- make a Dungeness crab salad with vinaigrette and it can seem a little mingy; bind it with mayonnaise and it’s practically guaranteed to be amazing.

Perhaps the easiest and most common cooked-oyster recipe is for stew. Small wonder there are about a million variations. At its most basic, an oyster stew can be nothing more than oysters warmed in light cream. If the oysters are good, this two-ingredient dish can be surprisingly delicious.

But why stop there? My favorite oyster stew is not all that much more complicated to make, but it adds more layers of flavor. Start by stewing prosciutto, leeks and shallots in butter. Add wine and reduce it, then bring half-and-half to a bare simmer. When bubbles begin to appear around the rim of the pan, add the oysters and cook just until they’re done. What brings all of the flavors into focus is a last-minute garnish of chopped tarragon (oysters love licorice flavors almost as much as they love cream).

If you’re cooking the oysters in the oven, prop them on a bed of rock salt to ensure that the notoriously tippy shells stay upright, retaining all of the liquid. You can play with adding different ingredients to the salt. This doesn’t actually add flavor to the oysters (any more than the salt does), but scattering spices and dried herbs among the salt crystals before roasting can add an amazing aroma that lingers well after the pan is brought to the table.

Use that perfume to reinforce the flavors of the dish. Oysters roasted on a bed of braised fennel, finished with a little Pernod cream were really good (there’s that licorice thing again). But when I added fennel seed, chopped fennel stalks and black peppercorns to the rock salt, they seemed to take on another dimension.

Notice that when you’re roasting oysters, you’ll want to add a bit of fat to them too. All it takes is a very small amount of butter or cream to add a luscious sheen; any more and they’ll be swimming, and that’s not an improvement.

That, I think, is part of the magic of the Marshall Store barbecued oysters. That little brush with butter is enough to round out the flavor. The only problem with that preparation is that you have to be a pretty slick shucker to get enough oysters ready for grilling in time.

Trying to duplicate the dish at home, I came up with what I think is an elegant compromise. Make chipotle butter by pureeing canned chipotles and garlic in a blender, then streaming in melted butter. Then, instead of shucking the oysters, brushing them with butter, grilling them, then saucing them, I just give them a brief roast first to loosen the shell, and then spoon on just a dab of the chipotle butter before returning them to the oven to glaze.

This is different than the original, both in process and in finished result. The flavors are brighter and more assertive, and there is a distinct prickle of chile heat that isn’t as obvious in the Marshall Store version.

The most obvious difference, of course, is that you won’t have the icy waters of Tomales Bay at your feet. Still, this dish is so delicious that it is more than enough to keep you -- and your oysters -- smiling until the next time you do.