To paraphrase the baker and author Daniel Leader: if I could convince you of one thing, it’s to bake with a levain. Here’s how I made mine.

My recipes specify measurements in grams. I suppose I could buckle under to convention and provide (shudder) imperial volume equivalents, but trust me, you’re far better off investing in a $25 digital kitchen scale. While you’re at it, pick up a pizza stone, and you’ll be ready to make the best bread you’ve ever tasted. Bon appétit!

Steps

1. Prepare the apple water: Let 1 quart of tap water sit out overnight to remove any chlorine.
2. Look for hazy apples, preferably from a farm stand (the haze is wild yeast). Cut one apple into 1-inch chunks and place the chunks, along with the peel of the second apple, into a container with 1 cup of the water. (Cover and reserve the remaining water for later.)
3. Let the apple and water sit, covered, at room temperature, for three days, stirring daily. The mixture should be foaming a bit and should smell somewhat like cider by the third day.
4. Building the levain, Day One: Combine 50 grams of whole-wheat flour with 350 grams unbleached all-purpose or bread flour (the additional protein in bread flour may be beneficial for the early starter).
5. Measure out 150 grams of the apple water through a fine strainer and add 150 grams of the flour mixture (you’ll use the rest of the flour later). Whip vigorously with a whisk, scrape down the sides, and cover with a screen (a frying-pan spatter screen is ideal) or cheesecloth.
6. Leave the levain at room temperature, whipping every few hours to incorporate air. It is important to keep the starter aerated during the first few days.
7. Building the levain, Day Two: Add 75 grams of the reserved tap water and 75 grams of the flour mixture, whip, and leave at room temperature, covered as before, for another 24 hours, again whisking occasionally. You should see bubbles starting to form and the mixture increasing in bulk.
8. Building the levain, Day Three: Transfer the levain to a clean 2-quart container. Avoid transferring any of the dried bits from the sides of the old container.
9. Add 75 grams each of the reserved flour and tap water, whip, and cover as before.
10. If at any point in this process the levain starts to smell a bit funky, discard half, replace with equal parts (by weight) flour and water, and whip more frequently. If the levain seems limpid (not rising and bubbling), increase the frequency of feedings.
11. Building the levain, Day Four: Feed the levain once again with the remaining 100 grams of flour and 100 grams of water, and let it sit at room temperature for 2 to 3 hours. Your levain should now be ready for use, although it will continue to develop flavor over the next few weeks.
12. Care and feeding of your levain: Store the levain in a covered container in the refrigerator. For the first few weeks, feed twice a week as described in the next step; afterward, a weekly feeding is sufficient.
13. To feed, stir thoroughly and discard about 250 grams of levain. Replace with 125 grams water (straight from the tap is fine if your water isn’t too chlorinated) and 125 grams flour (either unbleached bread or all-purpose) and stir well. Leave the lid ajar (so gases can escape) at room temperature for 2 to 4 hours before tightly covering the levain and returning it to the refrigerator.
14. If you bake regularly, feeding is simply part of preparing the levain for the bread, and no other feeding is necessary. You should always feed the levain several hours or the night before making bread, so replenish with the amount of levain the recipe calls for and you will maintain a constant supply of fresh levain with no effort.
15. Occasionally clean out your container with hot water (never soap) to remove the crud that forms on the sides.
16. If you want a stronger levain, leave it out overnight once in a while and feed with smaller “meals.”
17. You may see a puddle of liquid forming on top, a product of fermentation. It can simply be stirred back in, but when it accumulates too much, I like to pour it off. Weigh your levain beforehand and replace the discarded liquid with the same amount of water and flour (in a ratio of about 3 parts water to 1 part flour). Then feed as usual.