Though banana bread has become the unofficial sponsor of 2020, countless people are also trying their hand at baking traditional loaves. And this deep dive into domesticity has had an unexpected side effect: yeast is incredibly hard to find. Nielsen data from late March shows that yeast purchases were up by 231 percent as compared to last year. And while grocery shopping has since leveled off, it’s still difficult to find yeast in grocery stores. If you can’t get your hands on a packet of yeast, you can still bake gorgeous loaves by learning how to make sourdough starter.

Zachary Golper, chef and owner of Bien Cuit, a beloved bakery with three locations in New York City, says to make a beautiful loaf of bread without yeast you’re going to need a basic sourdough starter. Sourdough bread doesn’t require commercial yeast, says Golper, because it’s made with yeast that is harvested from the air.

“You’re harvesting wild yeast, and by wild I mean it’s floating in the air, it’s sitting on the skin of grapes and apples and any other fruit,” says Golper. “If you’ve got milled flour, there’s microbes of yeast in there. It’s just something that is sitting there dormant. And once you hydrate it, and it has access to its food source, it begins its life.”

With just grapes, flour, and water, Golper says you can make your own starter. But it takes some time—21 days to be exact. Don’t let that deter you: Golper says it’s well worth the wait. “Using slow fermentation with sourdough starter is essentially the key to delicious and digestible bread,” he says. “It also improves the shelf life.” And as long as you maintain your starter (more on that to follow), it can last forever. “You can maintain this cycle for as long as you live, and longer,” he says. “Your great grandchildren can continue.”

Golper was kind enough to share with Well+Good his tried-and-true sourdough starer and loaf recipes from his book, Bien Cuit: The Art of Bread.

How to make a sourdough starter

Ingredients

Day 1:8.8 ounces organic grapes (seeded or seedless, preferably locally grown)1/2 cup + 3 tbsp whole rye berries, ground into flour, or 1 cup + 1 ½ tsp dark rye flour

Days 3 through 6:2 ½ cups dark rye flour1 ½ cups + 3 tbsp water at about 60°F

Days 7 through 9:1 ½ cups + 1 ½ tbsp medium whole wheat flour3/4 cups + 3 tbsp water at about 60°F

Days 10 through 20:11 ¾ cups + 1 tbsp medium whole wheat flour6 ¾ cups + 2 tbsp water at about 60°F (15°C)

Day 21:1 cup + 1 tbsp medium whole wheat flour1/4 cup + 3 tbsp water at about 60°F

Day 1:

1. Wipe any dirt left from the grapes, but don’t immerse them in water. Puree in a blender or food processor. Transfer to a medium storage container, preferable one with high sides, and add the rye. Mix with your fingers, pressing the mixture into the sides, bottom, and corners until all of the flour is wet and fully incorporated. Cover and let sit at room temperature for 48 hours.

Days 3 through 6:

1. In a clean, high-sided storage container, combine 3/4 cup + 1 ½ tbsp of the flour and 1/4 cup + 3 tbsp of the water. Add 1/4 cup + 2 ½ tbsp of the Day 1 starter and discard the rest. Cover and let sit at room temperature.

2. Repeat the feeding every 24 hours, each time using 1/4 cup + 2 ½ tbsp of the previous day’s starter, for a total of four feedings.

Days 7 through 9:

1. In a clean, high-sided storage container, combine 1/2 cup + 1 ½ tsp of the flour and 3/4 cup + 3 tbsp of the water. Add 1/4 cup + ½ tbsp of the Day 6 starter and discard the rest. Cover and let sit at room temperature.

2. Repeat the feeding every 24 hours, each time using 1/4 cup + ½ tbsp of the previous day’s starter, for a total of three feedings.

Days 10 through 20:

1. In a clean, high-sided storage container, combine 1/2 cup + 1 ½ tsp of the flour and 3/4 cup + 3 tbsp of the water. Add 1/4 cup + ½ tbsp of the existing starter and discard the rest. Cover and let sit at room temperature.

2. Repeat the feeding every 12 hours, each time using 1/4 cup + ½ tbsp of the previous day’s starter, for a total of 22 feedings.

Day 21:

1. In a clean, high-sided storage container, combine the flour and water. Add 3 tbsp + 1 tsp of the existing starter and discard the rest. Cover and let sit at room temperature for six hours.

2. At this point it’s preferable to refrigerate the starter for 60 hours before using, but it will be fine to use after 12 hours.

3. Congratulations. You now have a healthy, happy starter!

Maintaining your starter:

1. Once every three days, remove the starter from the refrigerator for six hours. Remove and discard all but 3 tbsp + 1 tsp of the existing starter, then feed the starter using the same proportions as Day 21: 1 cup + 1 tbsp of whole wheat flour, 1/4 cup + 3 tbsp of water, and 3 Tbsp + 1 tsp of the existing starter. Cover and let rest for 6 hours, then return to the refrigerator.

2. If you plan on being away for more than 4 to 9 days, you need to slow the growth of the starter. Remove the starter from the refrigerator and discard all but 1/4 cup + 2 ½ tbsp of it. Let sit for six hours. Then add 5 ¼ cups + 2 tbsp of medium whole wheat flour and 1 ¼ cup + 3 ½ tbsp of water, and mix well to incorporate. Refrigerate for up to nine days.

3. If you’re going away for more than nine days, think of your starter as you would a pet. It’s a living thing that must be fed and watered. Get a friend to feed it according to the three-day feeding schedule.

30-Hour Sourdough Loaf

Ingredients

Starter:3 Tbsp + 1 tsp Sourdough Starter1/4 cup + 3 tbsp water at about 60°F1/2 cup + 3 ½ tbsp white flour

Dough:2 cups + 2 tbsp white flour, plus additional as needed for working with the dough1/2 cup + 1 ½ tsp medium whole wheat flour1/2 cup + 2 tbsp white rye flour3 tbsp + 1 tsp dark rye flour2 tbsp + 2 ¼ tsp buckwheat flour2 ½ tsp fine sea salt1 ¼ cup + 3 ½ tbsp water at about 60°F

Dusting mixture:1 part fine semolina flour5 parts white flour

For the starter:

1. Put the sourdough starter in a medium storage container and add the water. Break the starter into pieces with your fingers until it’s almost dissolved in the water; there will still be some small pieces. Stir in the flour until fully incorporated. Cover the container and let sit at room temperature for 10 to 14 hours. It will be at its peak at around 12 hours.

For the dough:

1. Stir together the white, whole wheat, white rye, dark rye, and buckwheat flours and the salt in a medium bowl.

2. Pour about one-third of the water around the edges of the starter to release it from the sides of the container. Transfer the starter and water to an extra-large bowl along with the remaining water. Using a wooden spoon, break the starter up to distribute it in the water.

3. Add the flour mixture, reserving about one-sixth of it along the edge of the bowl. Continue to mix with the spoon until most of the dry ingredients have been combined with the starter mixture. Switch to a  Plastic Bowl Scraper ($8) and continue to mix until incorporated. At this point the dough will be sticky to the touch.

4. Push the dough to one side of the bowl. Roll and tuck the dough, adding the reserved flour mixture and a small amount of additional flour to the bowl and your hands as needed. Continue rolling and tucking until the dough feels stronger and begins to resist any further rolling, about 14 times. Then, with cupped hands, tuck the sides under toward the center. Place the dough, seam-side down, in a clean bowl, cover the top of the bowl with a clean kitchen towel, and let rest at room temperature for 1 hour.

5. For the first stretch and fold, lightly dust the work surface and your hands with flour (not with the dusting mixture—save that for the lined proofing basket and shaped loaf). Using the plastic bowl scraper, release the dough from the bowl and set it, seam-side down, on the work surface. Gently stretch it into a roughly rectangular shape. Fold the dough in thirds from top to bottom and then from left to right. With cupped hands, tuck the sides under toward the center. Place the dough in the bowl, seam-side down, cover the bowl with the towel, and let rest for 1 hour.

6. For the second stretch and fold, repeat the steps for the first stretch and fold, then return the dough to the bowl, cover with the towel, and let rest for 1 hour.

7. For the third and final stretch and fold, once again repeat the steps for the first stretch and fold, then return the dough to the bowl, cover with the towel, and let rest for 30 minutes.

8. Line a 9-inch Proofing Basket ($18) or bowl with a clean kitchen towel and dust the towel fairly generously with the dusting mixture.

9. Lightly dust the work surface and your hands with flour and shape the dough into a round. Dust the sides and top of the dough with the dusting mixture, fold the edges of the towel over the top, and let rest at room temperature for 1 ½ hours.

10. Transfer the basket to the refrigerator and chill for 14 to 18 hours.

11. Position an oven rack in the lower third of the oven. Place a covered 6-quart, 10-inch round  Cast-Iron Dutch Oven ($70) on the rack. Preheat the oven to 500°F. Remove the basket of dough from the refrigerator and let it sit at room temperature while you allow the oven to preheat for about 1 hour.

12. Using heavy-duty oven mitts or potholders, remove the Dutch oven, place it on a heatproof surface, and remove the lid.

13. Using the kitchen towel, lift and gently ease the dough out of the basket and onto a baking peel, seam-side down. Then carefully transfer it into the pot (the Dutch oven will be very hot). Score the top of the dough, cover the pot, and return it to the oven. Lower the oven temperature to 460°F and bake for 30 minutes.

14. Rotate the Dutch oven and remove the lid. The loaf will already be a rich golden brown. Continue baking, uncovered, until the surface is a deep, rich brown, with some spots along the score being even slightly darker (bien cuit), about 25 minutes longer.

15. Loosen the edges of the loaf with a long handled spoon and then with the help of the spoon lift out of the pot onto a cooling rack. When the bottom of the loaf is tapped, it should sound hollow. If not, return it to the oven and bake directly on the rack for 5 minutes longer.

16. Let the bread cool completely before slicing and eating, at least 6 hours but preferably 12 to 36 hours.