The Fresh Loaf

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Purple Sweet Potato SD Milk Buns

Benito's picture

Purple Sweet Potato SD Milk Buns

For the dinner party last night we had one guest who won’t eat cooked vegetables!  What to prepare that he will eat?  Pulled pork sandwiches as the main, along with coleslaw.  For appetizers I served pork, shiitake mushroom and Napa gyoza that I made a while ago and froze.  These are great to have frozen so you can save prep when having a dinner party.  The pulled pork was made using my Instant Pot.

So for the buns I had previously purchased a few nice purple sweet potatoes, then cooked and mashed them, portioning them out into small ziplock bags and put them in the freezer for future use to save time for baking.  

For 8 buns

egg wash: 1 yolk, 1 tbsp milk and a pinch of salt, beaten…




Mix the levain ingredients in a jar or pyrex container with space for at least 300% growth. 

Press down with your knuckles or silicone spatula to create a uniform surface and to push out air.

At a temperature of 76ºF, it typically takes up to 10-12 hours for this stiff  sweet levain to be at peak.  For my starter I typically see 3-3.5 times increase in size at peak.  The levain will smell sweet with only a mild tang.



In a sauce pan set on medium heat, stir the milk and flour until blended. Then cook for several minutes until well thickened, stirring regularly with a spoon or heat-resistant spatula. Let cool in the pan or, for faster results, in a new bowl.  Theoretically it should reach 65ºC (149ºF) but I don’t find I need to measure the temperature as the tangzhong gelatinizes at this temperature.  You can prepare this the night before and refrigerate it, ensure that it is covered to prevent it from drying out.



In the bowl of a stand mixer, add the milk (consider holding back 10 g of milk and adding later if this is the first time you’re making this), egg, tangzhong, salt, sugar and levain.  Mix and then break up the levain into many smaller pieces.  Next add the flour, I like to use my spatula to mix until there aren’t many dry areas.  Allow the flour to hydrate (fermentolyse) for 15 minutes.  Mix on low speed and then medium speed until moderate gluten development this may take 5-10 mins.  You may want to scrape the sides of the bowl during the first 5 minutes of mixing.  Next drizzle in the melted butter a little at a time, or alternatively add soft room temperature butter one pat at a time.  Slow the mixer down to avoid splashing the butter at you. The dough may come apart, be patient, continue to mix until it comes together before drizzling or adding in more butter.  Once all the butter has been added and incorporated increase the speed gradually to medium.  Add the mashed potatoes gradually.  Mix at medium speed until the gluten is well developed, approximately 10 mins.  You will want to check gluten development by windowpane during this time and stop mixing when you get a good windowpane.  You should be able to pull a good windowpane.

On the counter, shape the dough into a tight ball, cover in the bowl and ferment for 2.5-3.5 hours at 82ºF.  There should be some rise visible at this stage.


You can next place the dough into the fridge to chill the dough for about 1.5 hours, this makes rolling the dough easier to shape.  Remember, if you do so the final proof will take longer.  Alternatively, you can do a cold retard in the fridge overnight, however, you may find that this increases the tang in your bread.


Line a large cookie tray with parchment paper.  Punch the dough down and then divide into 8 equal portions.  Form each into tight boules.  Place on a parchment lined cookie tray.  Cover them and allow them to fully proof about 4-6 hours, they should pass the poke test.


After about 30 mins of proofing time, whisk your remaining egg and milk and then brush the small boules.


About 30 mins prior to end of final proof preheat the oven to 350°F. 

Immediately prior to baking brush the dough again with the egg and milk mixture.  Top with sesame seeds.


Bake the buns uncovered for 30-35 minutes or until the internal temperature is at least 190F. Cover if your rolls get brown early in the baking process.



Remove the buns from the oven and transfer to a rack to cool.

These buns were so soft with a hint of sweetness and pretty colour from the purple sweet potatoes.  They will stay fresh for quite a while in a sealed plastic bag because of the tangzhong.  For a hardy sandwich or burger the 110 g dough weight per burger was perfect.

My index of bakes.


Isand66's picture

These look perfect for your pulled pork or a burger.  I’m surprised you were able to get such large buns at only 110 grams.  I usually do 135-150 grams but I guess it depends on how big your burger is.

I just baked some rolls as well that came out very well that I’ll post as soon as I get a chance.  
Happy baking!


Benito's picture

Thank you Ian, these turned out to be just the right size for the pulled pork sandwiches that we serviced.  As we get older we don’t eat quite as much and neither do our guests so no reason to make the buns larger for us.

I’ll look forward to your rolls you made.

Happy baking.