Here's your container of starter.

1) Add 1/4 cup lukewarm water to the starter in the container. Stir to dislodge the starter, and shake/stir to combine. Pour into a large glass or ceramic bowl.

2) Add 1 1/4 cups lukewarm water and 2 cups King Arthur Unbleached All- Purpose Flour (hereafter known simply as "flour"). Mix till well combined.

3) Cover the bowl with plastic wrap, and let sit at room temperature (about 70°F) for 8 to 12 hours.

4) After 8 to 12 hours, the starter will be bubbly.

5) Stir the starter, and discard about half. Mix in 1/2 cup lukewarm water and 1 cup flour.

6) The starter will be fairly thick, like pancake batter.

7) Cover the bowl, and let sit at room temperature for another 2 to 4 hours, till bubbly.

8) Stir the starter, and divide it in half; discard half, or give to a friend.

9) Feed the remaining half with 1/2 cup lukewarm water and 1 cup flour.

10) Again, the batter will be thick. Lumps are OK; don't bother to stir them out.

11) Cover the starter, and let it rest at room temperature for another 2 to 4 hours.

12) The starter will be bubbly, though not as bubbly as it might have been after its earlier rises.

13) Stir the starter down. Place it in a stoneware or glass container, loosely covered with a lid, or a screw-on top, not fully screwed on. Refrigerate it until you're ready to use it in a recipe.

To make "fed" sourdough starter

Most sourdough recipes will call for 1 cup or so of "fed" sourdough starter. Here's how to turn your refrigerated starter into "fed" starter.

1) Up to 12 hours before beginning a recipe, stir the starter and discard 1 cup. Or give 1 cup to a friend, or use 1 cup to make waffles. However you do it, you want to get rid of 1 cup of starter.

2) Feed the remaining starter with 1/2 cup lukewarm water and 1 cup flour.

3) Let it sit at room temperature, covered, for 4 to 12 hours, till bubbly. It's now "fed" and ready to use in a recipe.

4) Once you've removed however much starter your recipe calls for (usually 1 cup), feed the remainder with 1/2 cup lukewarm water and 1 cup flour. Let this remaining starter sit, covered, at room temperature for 2 to 4 hours, until bubbly.

5) Stir down, return to its container, and refrigerate.