Sourdough Potato Bread
A soft, tender sandwich loaf made with a ripe sourdough starter and mashed russet potato. The potato holds moisture, so the crumb stays plush and the bread keeps well for days, with a gentle tang and a golden, butter-brushed crust.
- Prep
- 1 hr
- Cook
- 1 hr
- Wait
- 8 hr 45 min
- Total
- 10 hr 45 min
- Makes
- 1 loaf (12 slices)
Steps
Before you start
- Feed your starter 4–8 hours ahead with equal weights of flour and water. Use it when it has doubled and is domed and bubbly. A starter that floats in water is a good sign, but the doubling matters more.
- Read the timing first. This loaf takes about 10¾ hours start to finish, mostly hands-off. Most of that is the bulk rise (about 4½ hours at 75–78°F / 24–26°C) and the final proof.
- Use a plain russet (starchy) potato with no butter, milk, or salt added. Waxy potatoes make a gummier dough.
- Measure the flour, potato, and starter by weight if you can. Mashed potato is hard to measure by volume and affects dough hydration.
Boil the potato
- Peel the russet potato and cut it into 1-inch (2.5 cm) chunks so they cook evenly.
- Put the chunks in a medium saucepan with the 2 cups (480 ml) water, which should just cover them.
- Bring to a boil over medium-high heat, then reduce to medium so the water simmers steadily.
- Cook for about 15 minutes, uncovered, until a knife slides into a chunk with no resistance and the edges start to crumble.
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Ready when: A knife slides into the center of a chunk with no resistance and the edges begin to crumble.
Tip: Start the potato in cold water, not boiling water, so the outside doesn't turn mushy before the center cooks.
Mash and cool
- Drain the potato very well and return it to the hot, dry pan for 1 minute to steam off moisture.
- Mash until completely smooth with a masher or ricer, with no lumps.
- Weigh out 200 g (about 1 packed cup) into a bowl and spread it out.
- Let it cool to lukewarm, below 90°F (32°C), about 25 minutes.
- Discard any extra potato or eat it.
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Ready when: Potato is smooth and feels barely warm to the touch, below 90°F (32°C).
Tip: Hot potato will damage the starter and over-ferment the dough. Check with a thermometer if unsure.
Mix and rest dough
- In a large bowl, stir together the lukewarm milk, sourdough starter, cooled mashed potato, and sugar until mostly combined and lumpy-looking.
- Add the bread flour and mix with a wet hand or a firm spatula until no dry flour remains and the dough is shaggy and sticky.
- Cover the bowl and rest for 30 minutes.
- This rest hydrates the flour and makes kneading easier.
- Do not add the salt or butter yet.
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Ready when: No dry flour is visible and the dough is shaggy, sticky, and cohesive.
Tip: Make sure the potato is fully broken up into the liquid before adding the flour so no streaks remain.
Knead in salt and butter
- Sprinkle the fine sea salt over the dough, then add the softened butter in small pieces.
- Squeeze and fold the dough with wet hands in the bowl for about 3 minutes to incorporate them, then turn it out onto a lightly floured surface.
- Knead for 6–8 minutes, pushing it away and folding it back, until it is smooth, elastic, and slightly tacky.
- It should clean the surface without sticking heavily.
- Return it to the bowl, smooth side up.
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Ready when: Dough is smooth and elastic, stretches thin without tearing when you pull a small piece, and is only slightly tacky.
Tip: Potato dough stays softer and stickier than regular dough. Use a bench scraper and a little flour rather than adding a lot more flour.
Bulk ferment with folds
- Cover the bowl and keep it at 75–78°F (24–26°C).
- At 30, 60, and 90 minutes, do a set of stretch and folds: wet your hand, grab the edge of the dough, stretch it up, and fold it over the center.
- Turn the bowl a quarter turn and repeat 4 times per set.
- After the third set, cover and leave it undisturbed until the dough has risen by about 50–75% (about 4½ hours total from the start of bulk).
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Ready when: Dough has grown by about 50–75%, is domed with bubbles on the surface and around the edges, and feels airy and jiggly.
Tip: Go by the dough, not the clock. In a warm kitchen it may be ready in 3½ hours, in a cool one it may need 5–6.
Pre-shape and rest
- Lightly flour a work surface and scrape the dough out gently.
- Pat it into a rough 8×10-inch (20×25 cm) rectangle, then fold it into thirds like a letter.
- Turn it seam side down, cover with a towel or plastic wrap, and let it rest for 20 minutes so the gluten relaxes.
- Meanwhile, grease the 9×5-inch (23×13 cm) loaf pan generously with half of the softened finishing butter.
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Ready when: Dough feels relaxed and spreads slightly when pressed.
Shape into the pan
- On a lightly floured surface, press the rested dough into a rectangle about 9 inches (23 cm) wide and 12 inches (30 cm) long, pressing out large bubbles.
- Starting from a short side, roll it up tightly into a log, tucking and pinching as you go to build surface tension.
- Pinch the seam and ends closed.
- Place it seam side down in the greased pan, pressing into the corners.
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Ready when: The log is tight and smooth on top, with the seam fully sealed and the dough touching all sides of the pan.
Tip: A loose roll bakes up with tunnels and a gap under the crust, so roll firmly.
Final proofOven 375°F / 190°C
- Cover the pan loosely with greased plastic wrap or a damp towel.
- Proof at room temperature, 75–78°F (24–26°C), for 90–110 minutes, until the dough crests about 1 inch (2.5 cm) above the rim of the pan and springs back slowly when poked lightly.
- About 30 minutes before the end, place a rack in the lower third of the oven and start preheating.
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Ready when: Dough crests about 1 inch (2.5 cm) above the rim and a floured fingertip leaves a dent that fills back in slowly, only partway.
Tip: If the dent springs back instantly, give it more time. If it doesn't fill back at all, bake right away. Preheat to 375°F (190°C).
Bake the loafOven 375°F / 190°C
- Bake on the lower-middle rack at 375°F (190°C) for 40–45 minutes.
- If the top browns too quickly after 25 minutes, tent loosely with foil.
- The loaf is done when the crust is deep golden brown and sounds hollow when tapped on the bottom after being turned out of the pan.
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Ready when: Deep golden crust, hollow sound when the bottom is tapped, and an internal temperature of 195–205°F (90–96°C).
Tip: Check the internal temperature with an instant-read thermometer in the center. Underbaked potato bread turns gummy.
Brush and cool
- Turn the loaf out of the pan right away onto a wire rack.
- Melt the remaining finishing butter and brush it over the top and sides for a soft, shiny crust.
- Cool completely, at least 90 minutes, before slicing.
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Ready when: The loaf feels fully cool to the touch on the bottom and sides.
Tip: Slicing while warm squashes the crumb and makes it seem gummy, because the starches are still setting.
Good to know
Tips
- Don't skip the 30-minute rest before adding salt and butter. It makes the sticky potato dough much easier to knead.
- Dough that seems very wet at first firms up as it ferments and as you fold it. Resist adding more than a tablespoon of flour.
- Mash the potato until perfectly smooth. Lumps leave pockets of gummy crumb in the slices.
- Check the dough's rise rather than the clock, since starter strength and kitchen temperature change the timing a lot.
Make ahead
"For a more sour flavor and easier timing, shape the loaf into the pan and cover tightly, then refrigerate for 8–12 hours instead of proofing at room temperature. Bake straight from the fridge, adding 5 minutes to the bake time, once the dough has risen to just above the rim. The mashed potato can also be made a day ahead and refrigerated; bring it to room temperature before mixing."
Storage & reheating
"Room temperature: keep in a bread bag or sealed container for up to 4 days. Refrigerator: not recommended, as it dries out the crumb. Freezer: slice, wrap tightly, and freeze for up to 3 months. Toast slices straight from frozen, or thaw at room temperature for 1 hour. Refresh a whole loaf in a 350°F (175°C) oven for 8–10 minutes."
Substitutions
- bread flour → All-purpose flour. Works well but the loaf will be a little softer and may need 2–3 tbsp (15–25 g) less milk to handle easily.
- russet potato → Yukon Gold potato. Gives a slightly yellower, creamier crumb. Mash well and weigh out 200 g as written.
- whole milk → Water or the potato cooking water. Gives a slightly chewier crust and less rich crumb. Cool it to lukewarm first.
- unsalted butter → Olive oil (3 tbsp / 40 ml). Makes the loaf dairy-free in the dough, but with a less buttery flavor.