SOURDOUGH STARTER

Steps:

• Mix together both flours. Measure 45 grams flour mixture (about 1/4 cup), setting the rest aside. Place in a bowl or container (we use a quart takeout container, so it's easy to watch grow). Add a scant 1/4 cup lukewarm water (45 grams) and mix until it creates a thick batter. Keep at room temperature, covered with a kitchen towel.
• Repeat feedings of 45 grams each water and flour mixture once a day at the same time, mixing with a rubber spatula, for 4 days. In the beginning you won't notice much movement; by the end, the starter should appear lively, with a bubbly appearance.
• On the 5th day, switch to entirely white flour and water, and start feeding twice-once in the morning and once at night. (At first you may smell some strong, not-very-pleasant smells, but eventually the starter will smell nutty and a little sour but pleasant.) Once it ferments-predictably rises, doubling in volume and creating a porous, webby-looking mixture after feedings-it is ready to use; this took us about 7 days. From this point, refrigerate your starter completely covered with the container lid.
• Start a regular feeding schedule-at least once or twice a week. For each feed, to maintain a large starter, remove all but 100 grams (discard the rest, or use for another purpose, such as our banana bread and cookies recipe), and add 100 grams each all-purpose flour and water.
• To maintain a smaller starter, remove 40 grams (discarding or using the rest), and feed with 40 grams each all-purpose flour and water. In the latter case, you may need to build your starter up to have amounts you'll need for recipes with leftover to maintain it; just feed without discarding for a couple of days in advance of when you'll need it.