Step 1

Select a container for your starter. A "starter" is a slurry of flour and water, and it provides the vehicle in which your yeast will propagate. You need a high concentration of yeast to leaven your bread, so you have to get a colony going before you can start baking. Any glass or plastic container with a lid will work for a sourdough starter.Canning jars are excellent, as are empty pickle or jam jars.Be sure the jar is clean, so the started doesn't get contaminated.

Step 2

Fill the container with equal parts flour and water. Mix equal parts flour and water in a separate bowl (the amounts aren't important, as long as you mix enough to fill your jar most of the way). Stir until thoroughly blended. Pour the mixture into your starter jar, leaving just a little room for air.Any type of flour will do, but remember that you need a good amount of gluten for your bread to rise properly (wheat, barley, and rye contain gluten).

Step 3

Place the container in a warm, dark location. There will be plenty of yeast in your mixture already, as they are present in the air and in the flour. Yeast like 4 things in order to reproduce: warmth, darkness, water, and starch or sugar. You have now provided all of those things, so your yeast should begin to reproduce rapidly. Leave the jar (with the lid on) alone for 24 hours.Room temperature is usually warm enough to provide the right conditions for yeast to grow. If your house is on the colder side, place the jar in a warm part of the kitchen.Cover the yeast jar with a heavy cloth to keep it dark.

Step 4

Feed your yeast every 24 hours. Once a day, pour half of the mixture out and replace it with a fresh batch of a mixture of half water, half flour. Within a week, your starter will develop a bubbly froth and a pronounced sour smell. When this happens, your starter is done, and you are ready to bake.

Step 5

Place the starter in the refrigerator. If you don't want to use the starter right away, park your jar in the refrigerator. Your yeast will stay alive in the cold, but they will remain in a state of sluggish dormancy. The starter can be left in the refrigerator indefinitely if you feed it once a week following the procedure outlined above.