Instructions: From Mendocino to Monterey, and everywhere in between, the meal of choice this time of year is steamed Dungeness crab, wine and San Francisco sourdough bread.

A quaint, crusty French-style loaf with a distinctive, almost startling sourness, San Francisco sourdough is unique to Northern California. Round or torpedo-shaped, it is a chewy, springy bread with a close, soft texture dotted with holes and containing a hint of moisture. The blistery crust is crackly and crisp.

Capturing the components of San Francisco sourdough has become a legendary quest among home bread bakers. I have plowed through much of the advice and recipes floating around since I started baking professionally in the 1970s, often ending up more perplexed than when I started. This time, however, I vowed to get it right.

My goal: a recipe for baking sourdough bread at home, without using special equipment, that was easy enough that a baker could succeed the first time. The taste, of course, had to be as close as possible to commercial San Francisco sourdough.

I did it, and you can, too. After a bit of experimentation, the recipe that I arrived at yields three or four loaves. Its not difficult, since most of the time is given to resting the dough, but its no last-minute project, either.

Start-to-finish time is 3 days.

My starter contains a dash of yogurt, but commercial breads are made from even simpler ingredients: just flour, salt, water and natural yeast. The ingredients are the same as when the bread first appeared during San Franciscos boomtown era around 1849. Back then, the Boudin bakery horse and wagon delivered fresh bread to homes around the city, hanging loaves on large nails by the front doors.

What makes sourdough unique is the mother, or starter. This thick mixture of flour and water is infused with tiny cells of wild yeast that settle in and grow, producing tiny bubbles of carbon dioxide that make the dough rise.

Frontier families, chuck wagon cooks and Basque shepherds treasured their pots of sourdough starter. It was the crucial ingredient for not only bread but also flapjacks and biscuits, and was even used as a poultice for healing wounds and gluing broken furniture. After each use, the starter was replenished with more flour and water to restore it to its original consistency and volume, ready for the next bake day.

Authentic strain

You can make a fine sourdough bread anywhere in the state, but to be a real San Francisco sourdough, the starter must contain wild yeast cells and Lactobacillus sanfrancisco, a strain of harmless bacteria (related to one that is naturally present in raw milk) that is said to be part of the citys fog-drenched environment.

The bacterium, which is responsible for the breads acidic flavor, was not isolated and named until U.S. Department of Agriculture biochemists analyzed the starters from five San Francisco bakeries for the first time in 1970.

Three years later, Sunset Magazine in conjunction with the Department of Food Science and Technology at the University of California-Davis, published directions for a yogurt-based starter and bread recipes. (The recipes are in later editions of the Sunset Cook Book of Breads, which is out of print. But if you own or can borrow a copy, the recipes will work with my starter.) The first commercially available freeze-dried starters appeared shortly after.

Who brought sourdough to San Francisco? Thats not clear. It may have been the skilled French bakers who came to San Francisco via Mexico or directly from France and the Basque country. They brought with them the Old World levain bread baking traditions of France and the Mediterranean. Levain is the French equivalent of sourdough starter, and pain au levain, sourdough country bread, is prized in France.

These early San Francisco bakers built handsome, notoriously idiosyncratic brick ovens with deep and shallow dome-shaped interiors. Typically, the ovens were underground, just below street level, and the bakeries were clustered around North Beach and lower Chinatown. Modeled on the wood-fired ovens of Europe, these ovens had no temperature gauge. They were manipulated by intuition and experience.

Used daily in the warm, protected environment of a bakery, a sourdough starter retains its leavening power and consistency. Since the yeast cells in the starter are constantly being infused back into successive doughs, many bakeries can trace their starters back generations.

For someone growing up in the Bay Area, there were always many choices of sourdough, even at the supermarket. A portion of the rounded heel of these thick tapered loaves would protrude from the stacks of bread on the shelf. And names such as Parisian, Franciscan, Bordenave, Ruby, Colombo, Toscana and Venetian were household words.

Boudin is the oldest sourdough French bakery, tracing its starter back to 1849 when Isadore Boudin, an apprentice baker from France, opened his first bakery on Grant Street in Chinatown. Boudin had carried his starter pot in his pocket during the long sea journey to San Francisco. Along with Parisian, which is predominantly wholesale and owned by a large baking conglomerate, Boudin is the only original bakery still in production and still shapes and scores bread by hand. The others folded one by one over the years, edged out by the highly mechanized mass production of loaves with longer shelf life from gigantic gas ovens.

Out of thin air

To make sourdough at home, you have to begin with a good starter. Real sourdough uses no commercial yeast. It just catches whatever is floating in the air and, under favorable conditions, the process of fermentation begins spontaneously. Depending on your catch, you can have a delicious or terrible starter. Lots of baking aficionados get some starter from a friend because it is much easier and less risky than catching your own.

When properly made, the starter, which bubbles and expands with enzyme action, smells like an earthy perfume, slightly sour and apple-like from malolactic fermentation. A bad batch will smell like bad cabbage. In my kitchen, the starter repeatedly turned pink, a sign of unwelcome bacteria, and had to be discarded.

I decided to try another approach. I had a sourdough bread recipe that was more than 10 years old from master baker Richard Marnhout, known in the South Bay for creating the wonderful artisan breads now sold at Draegers bakery and winning many bread competitions for his sourdoughs. This starter had added commercial yeast, creating what is called a yeast-fortified starter, also known as a levain-levure, which is made for each batch, an important technique if you only bake occasionally. I added a bit of yogurt for the touch of lactobacillus.

If you have some dehydrated starter, such as one packaged under Gold Rush Sourdough, sprinkle it in. The starter was easy to mix with a Kitchen Aid and, after sitting at room temperature, it quickly developed lots of bubbles and a clean, fresh acidic aroma. Already, I could tell I had a winner.

The main technique in making sourdough bread is to let the dough fully rest for long periods of time to develop the best flavor and texture. As Julia Child and Simone Beck say, The villain in the bread basket is speed.

I made both round and long loaves. Shaping is crucial, because it determines final crumb volume in the oven, and of course, appearance. Use a light, but firm hand, and make sure the loaves are pulled taut underneath. Rounds can go on a baking sheet. Long loaves are nice in the oblong Sassafras Superstone La Cloche French Bread Baker, which is available at Williams-Sonoma, but you can bake only one loaf at a time. The Chicago Metallic perforated Baguette Pan, a two-loaf cradle that shapes thick, long loaves, also works beautifully. Place the pan directly on a hot stone, and the heat comes in direct contact with the dough. A quick slash in the crust before baking lets the loaf develop its shape evenly.

Without a slash, it will tear.

Steam crucial to crust

Crust is crucial to sourdough. And the secret to the crust has always been steam. If you are using a La Cloche baker, dip the unglazed ceramic lid in water, set it in place and during baking, it will create a ready-made steamy environment. You can also rub a few drops of cold water gently onto the dough before placing loaves on a baking sheet. Or you can heat an empty metal baking sheet or roasting pan, adding 1 cup of boiling water to the heated pan and placing it in the oven when you bake your bread. This creates an instant cloud of steam, which gives the loaves a bit more volume. I always use a baking stone on the lowest third shelf for a nice hearth-like surface if Im not using my clay baker. Metal pans can be placed directly on it.

Store your sourdough in a paper bag, or just leave it on the counter. While plastic softens the crust, it will keep the inside of the bread moist. To freeze your bread, wait until it is completely cooled and place it in a freezer bag.

Reheat in a 350-degree oven for 7-10 minutes. If you know youre going to freeze some of the loaves, it helps to leave them a bit pale, a tip I learned from Boudin. Finish baking them later at 375 degrees for 10 to 14 minutes. That way, the loaf will be as crisp as when first baked.

The care and feeding of sourdough starter A good starter needs care and feeding. My recipe includes directions to make your first starter. If you have an existing starter or if you want to reserve 1/4 cup of mine for later use for bread, biscuits or pancakes, here are some maintenance tips:
Starters must be replenished after each use, or if they have been inactive for longer than about two weeks. Dont leave starter at room temperature longer than three days without feeding. Never add salt, which retards natural enzyme activity. If starter turns pink, it has bacteria and must be discarded.

You can keep sourdough starter going for years with careful feeding by adding equal parts of flour and water. Starter is at its most active six to 10 hours after feeding. To maintain, stir any separated yellowish liquid that has collected on top back into the starter. Then feed by adding equal amounts of bread flour and water in 1/2 cup or 1 cup increments. (If you have only a small amount, feed every three days to get the amount of starter you want.)

Place starter in a clean glass, ceramic or plastic container. Dont use stainless steel or aluminum, which will inhibit the growth of the wild yeast.

Cover with several thicknesses of cheesecloth or plastic wrap pierced in a few places and held in place with a rubber band. Let starter stand at room temperature overnight to two days, depending on how sour you want it. Stir it several times a day. It will bubble and expand. Feed the starter again and let it sit.

At this point, use the starter, refrigerate it or freeze it. Place the starter in the refrigerator, covered with a layer of plastic wrap held in place with a rubber band, or transfer to a heavy-duty zipper freezer bag. Sourdough starters can be frozen for months. Just defrost and start feeding to use again.

Beth Hensperger of Mountain View has written 12 baking books.

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