America's Test Kitchen Sourdough Bread Recipe: Slow-Fermented Crust With Open Crumb Mastery

America's Test Kitchen sourdough bread recipe delivers the perfect balance of a crispy, crackling crust and an airy, open crumb that bakers dream about. 🌟 This method transforms raw flour and water into artisanal bread with precision timing and traditional techniques that create restaurant-quality results at home.

The secret lies in the slow fermentation—letting the dough develop naturally over 12-16 hours at room temperature before a final cold proof in the fridge. This extended time builds deep flavor and creates that signature open crumb structure that separates great sourdough from good.

No Dutch oven? No problem—we’ll show you how to achieve that iconic oven spring with alternative methods.

By the time you pull this loaf from the oven, you’ll have a golden-brown crust with shatteringly crisp edges and a soft, chewy interior that practically melts in your mouth.

The aroma alone will have everyone gathering around the table, and the taste? That’s the real magic—tangy, complex, and satisfyingly rustic.

Whether you're a first-time baker or a seasoned pro, this recipe includes troubleshooting tips to handle common challenges like underproofed dough or uneven baking. We’ll also cover variations like adding whole wheat or seeds, so you can customize your loaf without sacrificing structure or flavor.

Ingredients for america's test kitchen sourdough bread

Flour, water, and patience transform into restaurant-quality sourdough with this precise ingredient lineup.

The flour is non-negotiable—King Arthur or Bob's Red Mill unbleached gives the best gluten development for that open crumb. King Arthur's high-protein flour is my go-to, but any bread flour works. Your sourdough starter should be 100% hydration and bubbly with a tangy aroma—if it smells like vinegar, feed it more. Water temperature matters: too hot and the yeast gets shocked, too cold and fermentation stalls. Room temperature (75°F) is ideal. For the Dutch oven, Lodge's cast iron is the gold standard, but any heavy pot with a lid works. If you're scoring, a lame or sharp razor creates clean cuts—no jagged edges.

No Dutch oven? A heavy baking sheet with a metal bowl upside-down underneath mimics the steam. Short on time? Instant yeast at half the amount can speed up fermentation, but you'll lose that signature sourdough tang. The optional whole wheat adds nutrition but can make the crust denser—replace 1:1 with all-purpose if you prefer a lighter loaf. Seeds add texture but burn easily, so toast them first to prevent scorching. For the sugar, white granulated is standard, but honey (1/4 cup) adds moisture and depth. Just beware—honey can make the crust too soft.

Store your starter in the fridge between bakes—it keeps 1-2 weeks if fed weekly. Flour lasts 6 months in a cool, dark pantry, while seeds stay fresh 1 year in the freezer. The scored loaf reheats beautifully: 5 minutes at 350°F restores that bakery-fresh crunch. Freeze unsliced loaves for 3 months—slice before toasting. For the Dutch oven, let it cool completely before washing to preserve that nonstick seasoning.

Step-by-step instructions for slow-fermented sourdough bread

Mastering this bread requires patience and precision—here's how to achieve that perfect open crumb and crispy crust.

In a large mixing bowl, combine the 4.5 cups unbleached all-purpose flour with the 1 cup active sourdough starter. Gently mix with a wooden spoon until just combined—no need to develop gluten yet. Add the 2.5 cups room-temperature water and mix again until a shaggy dough forms.

Cover the bowl with plastic wrap and let it rest for 30 minutes. This autolyse stage hydrates the flour completely and begins gluten development. You'll notice the dough become smoother and more cohesive—this is your first sign that fermentation is starting. If using the 0.5 cup optional whole wheat flour, replace 0.5 cups of the all-purpose flour now.

After the autolyse, sprinkle the 1.5 tsp kosher salt and 0.5 tsp olive oil over the dough. Using your hands, gently fold these ingredients into the dough until evenly distributed. The salt should dissolve completely, and the olive oil will give the dough a silky texture that improves handling.

Real talk: don't overwork the dough at this stage. You're just integrating the ingredients, not developing gluten. The dough should still look slightly shaggy with some dry spots—this is normal. Cover the bowl again and let it rest for another 30 minutes while you prepare your workspace.

After the second rest, perform a series of stretch-and-folds every 30 minutes for 2 hours. To do this, wet your hands slightly, grab one side of the dough, stretch it upward, and fold it over itself. Rotate the bowl and repeat on all sides. This builds strength without over-developing the gluten too early.

Let the dough ferment at room temperature (75°F) for 4-6 hours until it's increased by 50-75% in volume and looks puffy with bubbles throughout. The surface should be domed and slightly jiggly when gently shaken. If using the 0.25 cup optional seeds, sprinkle them evenly over the dough during the last hour of bulk fermentation.

Turn the dough onto a lightly floured surface and gently pre-shape it into a loose round. Cover with plastic wrap and refrigerate for 12-18 hours. This cold proof slows fermentation, allowing flavors to develop fully and gluten to relax. The dough should nearly double in size during this time.

After cold proofing, turn the dough onto a lightly floured surface and shape it into a tight round. The tension should be even all around—press gently to create surface tension without over-handling. This final shape determines your bread's structure and rise quality.

Preheat your dutch oven in the oven at 475°F for 45 minutes. While it heats, dust a baking sheet with 0.25 cup cornmeal. Turn the shaped dough onto the baking sheet, cover with a kitchen towel, and let it rest for 10 minutes while the oven finishes preheating.

Carefully transfer the dough to the hot dutch oven. Using the lame or sharp razor blade, score the dough in a simple crosshatch pattern—this controls expansion and creates those beautiful crust patterns. Bake covered for 20 minutes, then remove the lid and bake for another 20-25 minutes until the crust is deep golden brown.

For the ultimate test, tap the bottom of the loaf—it should sound hollow. Let it cool on a wire rack for at least 1 hour before slicing. The interior should reveal an open, airy crumb with a crispy, caramelized crust that's worth every minute of waiting.

Best sauces and condiments for this recipe

Classic Garlic Butter

Spread 2 tbsp softened unsalted butter mixed with 1 minced garlic clove and ½ tsp flaky sea salt on freshly baked sourdough. The butter melts into the crust, creating a rich, savory contrast to the tangy interior.

For extra depth, add ½ tsp lemon zest—it brightens the garlic flavor beautifully. 🧈

Olive Oil and Herbs

Drizzle 1 tbsp extra-virgin olive oil over warm slices, then sprinkle with 1 tsp chopped fresh rosemary or thyme. The oil enhances the bread’s natural nuttiness while the herbs add an aromatic finish.

I like to add a pinch of red pepper flakes for a subtle kick—just ¼ tsp to avoid overpowering the delicate crumb.

Whole Grain Mustard

Mix 1 tbsp Dijon mustard with 1 tbsp honey and brush onto toasted slices. The mustard’s tang cuts through the bread’s richness, while the honey adds a touch of sweetness that balances the sourdough’s acidity. This combo works especially well with toasted sunflower seeds sprinkled on top. 🌟

Spiced Honey Glaze

Heat 2 tbsp honey with ½ tsp cinnamon and ¼ tsp cayenne pepper in a small saucepan until warm. Brush over sliced bread for a sweet-spicy contrast. The cinnamon adds warmth, while the cayenne gives a gentle heat that pairs perfectly with the bread’s crusty exterior.

Store-bought honey works, but raw local honey deepens the flavor even more.

Balsamic Reduction

Simmer ¼ cup balsamic vinegar until reduced by half, then drizzle over warm slices. The vinegar’s acidity enhances the bread’s tang, creating a sophisticated flavor profile.

For extra richness, add 1 tbsp aged balsamic glaze at the end. This pairing elevates simple toast into a gourmet experience—perfect for brunch or charcuterie boards.

Frequently asked questions