Imelda, here is the recipe from King Arthur flour upon which I base mine. small print are changes I make
CLASSIC SOURDOUGH BREAD
STIR SOURDOUGH STARTER TO MIX IT WITH THE LIQUID WHICH HAS FORMED OVER IT. Pour off the liquid REMOVE 1 CUP OF THE STARTER AND REPLACE IT WITH 1 CUP OF FLOUR DISSOLVED IN 1 CUP OF WATER. I use less than 1 cup of water but usually more than half a cup LEAVE IT SETTING OUT, COVERED, 18- 24 HOURS. COVER STARTER AND REFRIGERATE i do not refrigerate it unless I plan to not use it for a while. Otherwise i feed it about once every 9 to 10 days.
1 C. SOURDOUGH STARTER
1 1/3 C. WARM WATER
5-6 CUPS UNBLEACHED ALLPURPOSE FLOUR It never takes 6 cups to form the dough as I make it and almost never needs as much as 5 cups.
1 T. SALT i usually use a scant Tablespoon salt
1 T. SUGAR (OPTIONAL) i always use sugar
1 t. BAKING SODA It does not hurt to leave this out
CORNMEAL TO SPRINKLE ON PANS. I use a french bread pan and spray it with oil.
THE SPONGE: POUR 1 CUP STARTER INTO A LARGE CERAMIC BOWL. ADD THE WARM WATER AND ABOUT 3 CUPS FLOUR. BEAT VIGOROUSLY WITH A SPOON OR WIRE WHISK. COVER SPONGE WITH PLASTIC WRAP AND SET ASIDE FOR AT LEAST 2 HOURS AND AS MANY AS 24 HOURS. I omit this step. Instant yeast will start to raise the dough almost immediately
THE DOUGH: AFTER THE SPONGE HAS BUBBLED AND EXPANDED, REMOVE THE PLASTIC WRAP. TO ABOUT 2 CUPS OF FLOUR, ADD THE SALT, SUGAR, AND BAKING SODA. STIR THIS INTO THE SPONGE UNTIL IT LEAVES THE SIDE OF THE BOWL. TURN OUT ONTO A FLOURED SURFACE AND KNEAD 4 TO 5 MINUTES. ADD FLOUR AS NEEDED TO MAKE A FAIRLY STIFF DOUGH. I add all the ingredients to the sponge, adding the yeast to the first cup of flour and the salt to the second cup. It almost always takes less than the full amount of flour when using a stand mixer before the flour leaves the bottom of the bowl clean and the dough comes together to form a ball. I leave the mixer running for a few minutes to continue to knead the dough.
GIVE THE DOUGH A REST WHILE YOU CLEAN OUT AND GREASE YOUR BOWL. CONTINUE KNEADING FOR ANOTHER 3-4 MINUTES. PLACE THE DOUGH IN THE BOWL AND TURN IT OVER TO GREASE THE TOP. COVER IT WITH PLASTIC AGAIN AND LET IT RISE FOR ANOTHER 2-4 HOURS. THIS SECOND RISING CAN BE SKIPPED BUT THE SECOND RISING WILL GIVE THE BREAD MORE FLAVOR. Since the flavor comes from the sourdough yeast, I find it unnecessary for the second rise since the dough will not really gain any more flavor from the instant yeast in the second rise. It takes 2 hours tops for the first rise. Usually less time.
SHAPING AND BAKING: KNOCK DOWN THE DOUGH AND SHAPE IT INTO TWO LONG FRENCH BREAD ROLLS. PLACE ON A CORNMEAL SPRINKLED COOKIE SHEET, COVER AND LET RISE FOR ANOTHER 2 HOURS OR SO.
TOWARD THE END OF THE RISING PERIOD, PREHEAT OVEN TO 450 DEGREES I bake at 430 degreese. AND BEGIN HEATING A KETTLE OF WATER ON YOUR STOVE. I usually forget to add steaming water to the oven. JUST BEFORE YOU PUT THEM IN THE OVEN SLASH THE TOPS OF THE BREAD DIAGONALLY WITH A KNIFE ABOUT 2 INCHES APART AND ABOUT 1/4 INCH DEEP AND BRUSH WITH COLD WATER OR, FOR A SHINY CRUST, BRUSH THEM WITH A WASH OF EGG MIXED WITH WATER. ALSO FOR A FESTIVE LOOK SPRINKLE THEM WITH SESAME OR POPPY SEEDS.
PLACE A PAN IN THE OVEN BOTTOM AND POUR IN 3 OR 4 CUPS OF BOILING WATER. PUT THE LOAVES ON THE RACK OVER THE STEAMING WATER, CLOSE THE OVEN AND BAKE FOR ABOUT 25 MINUTES. THE CRUST WILL BE VERY HARD WHEN YOU REMOVE THE BREAD FROM THE OVEN BUT IN ABOUT 5 MINUTES THE CRUST WILL CHEWY AND CRACKLING. TO KEEP THE CRUST CRUNCHY, LEAVE THE BREAD IN THE OVEN WITH THE OVEN OFF FOR ANOTHER 5 MINUTES. I put a probe thermometer in the crust after the bread has baked about 10 minutes and take it out when it reads 190 degrees which is usually only a few more minutes... less than 5 more minutes. The bread crust will soften after cooling, unless you leave it in the oven as the directions say.