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.
Marshall Store, 19225 State Route 1, Marshall (about 20 minutes north of Point Reyes); (415) 663-1339. Open 10 a.m. to 6 p.m. daily.