Sourdough Japanese Milk Buns

Japanese milk buns are the ultimate roll for both sweet and savory moments—perfect alongside breakfast, dinner, or anything in between. Imagine a soft, pillowy roll that pulls apart effortlessly, with a tender crumb that feels like a little bite of heaven.

These buns are made using the tangzhong method, a simple technique that locks in moisture and creates that signature ultra-soft, fluffy texture Japanese milk bread is known for. And thanks to the use of sourdough, you get all the benefits of natural fermentation—better digestion and deeper flavor—without any strong sour taste. Just a beautifully balanced, lightly sweet roll with a rich, comforting finish.

Whether you’re slathering one with butter and jam or stuffing it with something savory, these sourdough Japanese milk buns are about to become your new go-to bread for every meal.

Enjoying the softness of a freshly baked Japanese milk bun, perfect for a delightful treat.

Detailed Instructions + Pro Tips

Step 1: Make the Tangzhong

In a small saucepan over medium heat, whisk together the flour, water, and milk until smooth and lump-free.

Continue stirring constantly as the mixture heats. After about 2–3 minutes, it will begin to thicken into a soft, paste-like consistency—similar to pudding or mashed potatoes.

Once thickened, remove from heat and transfer the tangzhong to a small bowl. Press plastic wrap directly onto the surface (this prevents a skin from forming) and let it cool in the refrigerator until it is lukewarm or room temperature.

Tip: Tangzhong that’s too hot can damage your sourdough starter later, so make sure it’s no warmer than slightly warm to the touch.

Step 2: Mix the Dough

In a large mixing bowl, combine the cold milk and active sourdough starter. Stir until smooth.

Add the egg, cooled tangzhong, and sugar, mixing until the mixture looks slightly frothy and well combined.

Add your flour and mix until a shaggy, rough dough forms. Cover and let the dough rest for 30 minutes.

Why this rest matters: This short rest (autolyse) allows the flour to hydrate fully, making the dough easier to knead and improving the final texture.

After resting, sprinkle the salt over the dough and gently dimple it in with your fingers.

Transfer the dough to a clean, smooth work surface and knead for 2–3 minutes to incorporate the salt.

Now place the softened butter on top of the dough and knead for another 10–15 minutes, until the dough becomes:

• Smooth and shiny

• Elastic and stretchy

• Able to pass the windowpane test

Tip: This is a rich dough, so it may feel slippery at first when adding butter—keep kneading and it will come together beautifully.

Return the dough to the bowl and cover with a clean towel or plastic wrap.

Step 3: Bulk Fermentation (First Rise)

Let the dough rise in a warm, draft-free spot until it has increased in size by 50–60%. It will not double—this is normal for enriched sourdough dough.

At a dough temperature of 78–80°F, this will take about 5–6 hours.

You’ll know it’s ready when the dough looks puffy and slowly springs back when gently pressed.

Optional: Cold Proof for Better Flavor

After bulk fermentation, you may refrigerate the dough for 6–8 hours (or overnight).This step improves flavor, structure, and makes the dough easier to handle the next day.

Tip: If chilling overnight, let the dough sit at room temperature for about 30 minutes before shaping.

Step 4: Shape the Rolls

Divide the dough into 9 equal pieces (about 85g each). Shape each piece into a tight, smooth ball by tucking the edges underneath and rolling gently against the counter.

Place the rolls in a parchment-lined casserole dish or baking pan, spacing them evenly.

Cover loosely with a towel or plastic wrap and allow them to rise until doubled in size, about 2–3 hours at 78–80°F.

Warm-proofing tip: If your home is cool, place the pan of rolls in your oven (turned off) with the light on and the door slightly cracked. This creates the perfect warm environment for rising.

The rolls are ready to bake when they look pillowy and slowly spring back when touched.

Step 5: Bake the Rolls

Preheat your oven to 350°F (175°C).

Brush the tops of the rolls gently with egg wash for a shiny, golden finish.

Bake for 22–25 minutes, until the rolls are lightly browned and the internal temperature reaches 195°F.

Remove from the oven and immediately brush the tops with melted butter for extra softness and flavor.

Pro tip: Cover loosely with a clean towel while cooling to keep the rolls extra soft.

Example Baking Schedule

10am mix dough

3pm shape rolls

6pm bake

Recipe

Servings: 9 rolls Prep time: 12 hours (including rising) Baking time: 25mins

Ingredients

Tangzhong mixture

• 20 g all-purpose flour

• 27 g water

• 60 g whole milk

Dough

• 100 g active sourdough starter

• Tangzhong (from above)

• 340 g all-purpose flour

• 60 g sugar

• 6 g salt

• 90g whole milk

• 1 large egg (50 g without shell)

• 42 g unsalted butter, very soft

Egg wash

• 1 egg

•1 Tbsp water

Instructions

Step 1: Make your Tangzhong mixture

In a small saucepan heated to a medium heat combine your flour, water, and milk. Constantly stir this mixture until it begins to thicken. (2-3 minutes) Once you have a paste-like texture, transfer your Tangzhong to a small bowl, cover with plastic wrap, and put into the fridge until it is slightly warm or room temperature.

Step 2:Mix the dough

In a large bowl add your cold milk and active sourdough. Mix well. Add your egg, cooled Tangzhong, and sugar. Mix until frothy.

Add your flour and combine until you form a shaggy dough. Rest for 30 minutes.

Dimple in the salt with your fingers and transfer your dough to a smooth clean surface. Knead for 2-3 minutes.

Place your softened butter on top of the dough and knead for another 10-15 minutes. Until your dough is smooth, elastic, and passes the windowpane test.

Transfer your dough back to the bowl and cover with a clean towel or plastic wrap.

Step 3: Bulk Fermentation

Allow your dough to rise until it has increased 50-60% in size. It will not double. If the dough is 78F-80F this should take 5-6 hours.

Optional cold proof

After you're done bulk fermenting you can refrigerate your dough for 6-8 hours for better flavor and structure.

Step 4: Shaping

Divide your dough into 9 equal pieces (~85g each) and shape into tight balls. Place into a casserole dish or pan lined with parchment paper.

Cover with a towel or plastic wrap and allow to rise until doubled in size. This will take 2-3 hours if your dough is 78F-80F

Tip: If your home is cold, place your dough in the oven (no added heat) with the oven light on and the door cracked open. This will keep your dough warm and allow it to rise faster.

Step 5: Bake

Preheat your oven to 350F

Brush your rolls with an egg wash and bake for 22-25 minutes. Your rolls should be lightly browned with an internal temperature of 195F.

Brush with melted butter immediately after baking and enjoy!