Soft, fluffy, naturally fermented buns made with roasted sweet potatoes
These sweet potato sourdough hamburger buns are incredibly soft, moist, and lightly sweet with the perfect pillowy texture. The addition of mashed sweet potatoes keeps the buns tender, while sourdough fermentation makes them easier to digest and full of flavor. Perfect for burgers, sandwiches, or breakfast buns.
🕒 Time & Yield
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Prep Time: 20 minutes
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Proofing Time: Overnight (with short same-day proof)
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Bake Time: 18–23 minutes
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Total Time: ~24 hours (mostly inactive)
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Yield: 10 sourdough hamburger buns
🥖 Ingredients
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180 grams lukewarm milk
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50 grams granulated sugar
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150 grams active, active sourdough starter
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58 grams unsalted butter, melted
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1 large egg, lightly beaten
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250 grams cooked sweet potatoes, mashed and cooled
(about 2 medium sweet potatoes, roasted at 375°F for 1 hour) -
500 grams all-purpose flour
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9 grams sea salt (about 1 tablespoon)
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flour, for dusting baking sheets
Optional
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1 teaspoon instant yeast (if your sourdough starter is not very active)
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Sesame seeds, for topping
Egg Wash
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1 large egg
Step-by-Step Instructions
1️⃣ Make the Dough
In the bowl of a stand mixer fitted with the dough hook, add:
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Milk
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Sugar
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Sourdough starter
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Butter
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Egg
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Mashed sweet potatoes
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Flour
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Salt
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(Optional yeast, if using)
Mix on low speed until the dough comes together. Increase to medium-low speed and knead for 10 minutes, until the dough is smooth and elastic and pulling mostly away from the sides of the bowl.
Note: This is a soft, slightly sticky dough — that’s what makes the buns so tender.
2️⃣ First Proof (Bulk Fermentation)
Transfer the dough to a lightly greased bowl. Cover and let rise at room temperature for 1½–2 hours, or until doubled in size.
3️⃣ Shape the Buns
Line two baking sheets with parchment paper and lightly dust with semolina flour.
Using lightly floured hands, divide the dough into 10 equal pieces. Shape each piece into a smooth, tight ball, building surface tension so the buns rise tall and round.
Place 4 – 5 buns per baking sheet, leaving plenty of space between them.
4️⃣ Second Proof + Overnight Fermentation
Cover the buns and let proof at room temperature for about 1 hour, until noticeably puffy.
Transfer the covered baking sheets to the refrigerator and let proof overnight. This slow fermentation improves flavor, texture, and digestibility.
5️⃣ Bake the Buns
The next day, preheat your oven to 375°F (190°C).
Brush the buns gently with egg wash and sprinkle with sesame seeds if desired.
Bake for 18–23 minutes, until:
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Deep golden brown
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Internal temperature reaches 190–200°F
Remove from the oven and cool on a wire rack.
Tips for Success
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Use fully cooled sweet potatoes so they don’t affect fermentation
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For extra-soft buns, brush lightly with melted butter after baking
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These buns freeze beautifully once fully cooled
Why Overnight Proofing Matters
Overnight proofing allows the dough to ferment slowly in the refrigerator, which greatly improves both flavor and texture. This extended fermentation gives the sourdough more time to break down gluten and sugars, making the buns easier to digest while developing a deeper, more complex flavor. The cold proof also helps the dough strengthen, resulting in a softer crumb, better structure, and taller, fluffier buns when baked. Slowing the process creates a more consistent rise and produces bread that stays fresh longer, making overnight proofing well worth the wait.
How to Use
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Sourdough hamburger buns
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Brioche-style sandwich buns
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Breakfast egg sandwiches
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Pulled pork or veggie burgers
