Purple Sweet Potato Sourdough

It is soft, light, purple… delicious 😋  That’s how I describe the purple sweet potato sourdough bread.

It is so much fun to work with the purple dough.

And how great is it to have a purple sandwich bread made from natural products?

Ingredients

Sourdough starter 

• 5g sourdough starter
• 35g water
• 30g all purpose flour or bread flour 
• 5g rye flour 

Dough

• 270g  high gluten flour (90%)
• 30g whole grain whole wheat flour (10%)
• 207g water (69%)
• 60g levain (20%) 
• 6g salt (2%)

After the dough is divided in two pieces:

• 9g water (6%) for the dough #1 
• 100g boiled and mashed purple sweet potato for the dough #2

Directions 

Starter

Night before

• 10 pm add starter to the water and whisk together, add flour, mix well, cover loosely, let it sit at room temperature at 74-78F until in about 10-12 hours starter reaches its peak (triples or more in volume).
• Boil purple sweet potatoes, let them cool overnight.

• Learn how to make starter from scratch here.

Dough

• 7 am mix water with bread flour and cover it, let it rest 1 hour for autolyse. During the autolyse process the flour absorbs water, becoming fully hydrated. This activates gluten development.
• 8 am add sourdough starter. 
• Mix on low speed of your mixing machine for 2-3 min, or KitchenAid on speed 3 for 3-4 minutes until well incorporated.
• Cover and let it rest for 30 min.
• 8:30 am add salt and mix on low speed of your mixing machine for 1-2 minutes, or KitchenAid on speed 3 for 2-3 minutes until well incorporated. 
• Divide the dough in 2 equal pieces.
• Add extra water to the dough #1
• Add purple sweet mashed potato to the dough #2.

• Using your hands or mixer incorporate water into the dough #1 and purple sweet potato into the dough #2.
• For both pieces the dough should come up together, but still be sticky. We will continue gluten development and structure building by performing stretches and folds during warm fermentation period. Cover both dough pieces.
• Leave to rest for 30 min. At 74-78F /23-26C.

Lamination 

• 9 am wet your hands and spray table with water. Stretch the first and second dough pieces separately, then place one on top of another, fold them and let rest 30 min.

• 9:30 am 1st stretch and fold.

• 10:15 am 2nd stretch and fold.
• 11:00 am 3rd stretch and fold. 
• Performing stretches and folds every 45 min will help to continue gluten development.
• Keep monitoring the dough, if it’s rising too fast, you can shorten time in between stretches to 40 minutes or less.
• After the final stretch let the dough proof for 40 minutes at 76-80F/ 23-26C. You should see some bubbles on the surface, the dough has to become lighter. We are looking for 40%-50% rise.

Preshaping

• 11:40 am transfer dough to a work surface and dust the top with flour. Then flip the dough over so the floured side faces down.
• Fold the dough onto itself so the flour on the surface remains entirely on the outside of the loaf. This will become the crust.
• Place the dough round on a work surface and let it rest for 30 minutes uncovered.

Shaping

• 12:10 pm dust the dough with flour. Use a dough scraper to flip it over onto a work surface so floured sides are facing down.
• Starting at the side closest to you, pull the right 2 corners of the dough to the left, then fold them up into half of the dough. Repeat this action on the left side too.
• Finally, roll the dough. Shape it into a smooth, taut roll.
• Transfer the roll, seam side up into a prepared proofing basket (loaf pan with kitchen towel)
• Cover it with plastic and return the dough to the 80F (27C) environment for 15 min.
• 12:25 pm transfer dough to rise for 14-24 hours in the refrigerator.

Baking

Next morning

• Preheat the oven to 500 F, place your cast iron pan with the lid inside for 45 minutes -1 hour.
• Remove the dough from the fridge.
• Flip it over on a parchment paper, score it with a sharp knife or a bread lame.
• Transfer it to the hot cast iron pan, cover it with the lid (to create steam for a beautiful and crusty crumb).
• Bake at 500F for 15 minutes with the lid on.
• Remove the lid, lower the temperature to 450F.
• Bake for 20 more minutes until golden brown.

Let it cool for 2 hours and enjoy your purple sweet potato sourdough.

Purple Sweet Potato Sourdough

1319kcal

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Prep 45 minutes mins

Cook 35 minutes mins

Rise & Rest Time 1 day d 1 hour hr 15 minutes mins

Total 1 day d 2 hours hrs 35 minutes mins

This visually spectacular artisan loaf showcases a striking marbled or vibrant purple interior crumb from real purple sweet potatoes. Soft, light, and delicious, this recipe splits a high-hydration base dough into two halves—one white, one purple—before using a lamination step to layer them together for a stunning swirl effect under a crackly, thin crust.

Cuisine Modern Artisan

Ingredients

Sourdough Starter Levain (Night Before)

• ▢ 5 g Sourdough starter culture
• ▢ 35 g Water
• ▢ 30 g All-purpose flour or bread flour
• ▢ 5 g Rye flour

The Main Dough Base

• ▢ 270 g High-gluten flour or bread flour (90%)
• ▢ 30 g Whole grain whole wheat flour (10%)
• ▢ 207 g Water (69% – Used for the core autolyse mix)
• ▢ 60 g Active sourdough starter levain (20% – From the stage above)
• ▢ 6 g Salt (2%)

Post-Division Adjustments (For Split Batches)

• ▢ 9 g Water (6%)
• ▢ 100 g Purple sweet potato (Boiled, mashed, and completely cooled)

Equipment

• ▢
  Stand Mixer (A KitchenAid or standard mixing machine handles the baseline gluten structure effortlessly)
• ▢
  Proofing Basket (Banneton or a clean bowl cleanly lined with a dry kitchen towel)
• ▢
  Cast Iron Pan with Lid (Or a heavy Dutch oven to capture pressurized steam for maximum oven spring)
• ▢
  Sharp Scoring Lame (Or a fresh razor blade for clean, decorative expansion cuts)
• ▢
  Parchment Paper
• ▢
  Kitchen Scale

Method

Prevent Sleep ModePrevent Sleep Mode

Night Before – Levain Optimization & Potato Prep

1. 10:00 PM – Starter Build: In a small glass jar, add your 5g of starter culture to 35g of water and whisk together cleanly. Stir in 30g of all-purpose or bread flour and 5g of rye flour. Mix thoroughly, cover loosely, and let it sit at room temperature 74–78°F (23–26°C) overnight for 10 to 12 hours until the starter reaches its peak and triples or more in volume.
2. Purple Potato Prep: Boil your purple sweet potatoes until fork-tender. Drain thoroughly, peel, and mash them with a fork or potato ricer until completely smooth and free of lumps. Let the mash cool completely down to room temperature overnight.

Day 2 – The Core Autolyse & Dual-Batch Splitting

1. 7:00 AM – The Core Autolyse: In your stand mixer bowl, combine the 270g of high-gluten flour, 30g of whole wheat flour, and 207g of water. Mix thoroughly with a spoon just until all dry flour patches entirely disappear. Cover tightly and let it rest on your counter for 1 full hour.
2. 8:00 AM – Sourdough Starter Integration: Add 60g of your active overnight starter peak directly into the autolysed dough. Turn your mixing machine on low speed for 2 to 3 minutes (or use a KitchenAid mixer on speed 3 for 3 to 4 minutes) until the starter is completely incorporated. Cover and let rest for 30 minutes.
3. 8:30 AM – Salt Incorporation & Division: Add your 6g of salt directly to the bowl. Mix on low speed for 1 to 2 minutes (or on a KitchenAid on speed 3 for 2 to 3 minutes) until well incorporated. Using a digital scale, divide the dough mass into 2 precisely equal pieces.
4. Blending the Inclusions: * Place Dough piece #1 into a bowl and mix in the extra 9g of water to increase its hydration. Place Dough piece #2 into a separate bowl and incorporate the 100g of cold mashed purple sweet potato. Use your hands or a mixer to fully combine each batch. Both pieces will feel sticky but should pull together into cohesive units. Cover both bowls and let rest for 30 minutes at 74–78°F (23–26°C).

Lamination Swirl & Bulk Fermentation Folds

1. 9:00 AM – The Grand Lamination: Wet your hands and spray your clean work surface lightly with water. Take Dough #1 (White) and stretch it out as thin as possible across the table without tearing the matrix. Repeat the exact same thin stretching action with Dough #2 (Purple) on another surface (or set the white sheet aside). Place the purple dough sheet directly on top of the white sheet. Fold the layered sheets neatly over on top of each other into a neat package to trap the colors, transfer to a bulk container, and let rest for 30 minutes.
2. 9:30 AM – 1st Stretch & Fold: Wet your hands slightly. Lift one side of the layered dough up cleanly from the container edge and fold it over the center. Repeat this action for all four quadrants of the dough mass to build structured vertical strength. Cover and let rest for 45 minutes.
3. 10:15 AM – 2nd Stretch & Fold: Execute your second structured round of quadrant folds to continue organizing the expanding, colorful gluten network. Cover and let rest for 45 minutes.
4. 11:00 AM – 3rd Stretch & Fold: Execute the third and final stretch-and-fold round. Cover and let the dough proof completely untouched for 40 minutes at a warm 76–80°F (24–27°C). The dough should look visibly lighter, show distinct surface bubbles, and hit a clean 40% to 50% volume rise.

Preshaping, Tension Rolling, and Cold Retard

1. 11:40 AM – Preshaping: Gently tip the expanded dough out onto your work surface and dust the top lightly with flour. Flip the mass over so the floured side faces directly down. Fold the outer edges cleanly onto itself so that the raw flour coating remains entirely on the outside of the loaf. Round the dough into a loose ball and let it rest on your counter completely uncovered for 30 minutes to relax the gluten network.
2. 12:10 PM – Final Shaping: Dust the top of the resting dough round with flour. Use a dough scraper to flip it over onto your counter so the floured side faces down. Starting at the edge closest to you, pull the two right corners of the dough outward and fold them up into the center. Repeat this exact matching movement across the left side. Roll the dough tightly away from you, shaping it into a perfectly smooth, taut, uniform roll.
3. Basket Stabilization & Fridge Retard: Transfer the shaped roll seam-side up into your well-floured proofing basket. Cover with plastic wrap and return the basket to a warm 80°F (27°C) environment for exactly 15 minutes to stabilize. Slide the basket directly into your refrigerator to rise slowly for 14 to 24 hours of cold fermentation retard.

Day 3 – Blazing Cast Iron Bake

1. Next Morning – Preheating: Preheat your oven to 500°F (260°C). Place your cast iron pan and lid onto the middle rack to heat up thoroughly for 45 minutes to 1 hour.
2. Scoring & Loading: Remove the cold purple dough basket from the fridge. Flip it over gently onto a sheet of parchment paper and score the smooth surface with one clean, long, deep cut using a sharp lame or razor blade to reveal the vibrant colors inside.
3. The Steam Bake: Transfer the dough carefully onto the smoking hot cast iron pan base, drop the heavy lid down tightly to lock in the steam, and bake at 500°F (260°C) with the lid on for exactly 15 minutes.
4. The Open Bake: Carefully lift the hot lid off to expose the loaf, lower the oven temperature to 450°F (232°C), and continue baking bare for an additional 20 minutes until the crust turns an incredibly deep golden-brown. Let cool on a wire rack for 2 full hours before slicing to reveal your gorgeous purple swirl crumb!

Nutrition

Calories1319kcalCarbohydrates275gProtein41gFat4gSaturated Fat1gPolyunsaturated Fat2gMonounsaturated Fat0.4gCholesterol9mgSodium496mgPotassium873mgFiber15gSugar5gVitamin A14198IUVitamin C3mgCalcium104mgIron16mg

Notes

• The Structural Advantage of High-Gluten Flour: Because you are adding a heavy load of dense, starchy mashed purple sweet potato to half of the batch, using a strong high-gluten flour or high-protein bread flour is non-negotiable. The white half of the dough acts as the primary anchor, maintaining a resilient, taut gluten network that structurally supports the weighted purple coils during the intense oven spring.
• Mastering the Splitting and Hydration Ratios: Splitting the dough after the salt incorporation step allows both colors to start with a unified base. Because mashed potatoes add an enormous amount of internal moisture but lack liquid fluidity, adding a quick 9 grams of adjustment water to the pure white batch ensures that both halves retain a perfectly matched, pliable elasticity during the lamination step.
• Why the Lamination Step Shapes the Visual Swirl: Rather than kneading the purple potato mash directly into the entire batch—which would muddy the colors into a singular dull hue—this recipe relies on separate incorporations followed by a single lamination overlay. Layering the thin white and purple sheets together at 9:00 AM results in a clean, high-contrast interior marbling effect when sliced.

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