It's been raining in Seattle, pretty much nonstop for the last 2 weeks (no surprise there) and I ran out of rainy day projects. Desperate to kill time I dug into my collection of cookbooks and found this recipe for Bánh Bò Khoai Tím (Purple Sweet Potato Rice Cakes). This recipe comes from a cookbook by Gia Chánh Hoa Hường, published in the early 70s. The cookbook belonged to my aunt and was passed down to me when she moved to California to be closer to her kids. Like all traditional recipes for Bánh Bò, the leavening comes from Cơm Rượu (fermented rice). If you don't have the time or patience the fermented rice starter...I guess you can replace it with some yeast and see how it always Play with Your Food!

Translated from the original recipe above:

-150g purple sweet potatoes
-350g sugar
-300g rice flour
-3 tbs Cơm Rượu
-pinch of alum
-180ml water from boiling the potatoes
-2 egg whites

Peel potatoes and measure out 150g. Cut potato into cubes and boil with a pinch of alum until potatoes are tender. Weigh the potato mixture and adjust to the liquid amount to get 330g (150g potato + 180g potato water = 330g). Mix together potato mixture, fermented rice and rice flour until a smooth dough is achieved. Proof overnight.

Beat egg whites and sugar to stiff peaks, add the fermented dough and continue to achieve a homogenous mixture. Proof until batter doubles in volume. Steam in porcelain tea cups over high heat for 12 mins.

Comments (15)

On 3:02 AM , Rosa's Yummy Yums said...

They look so pretty! Love that color!



On 6:14 AM , lilyng said...


i am glad you are posting again. How have you been?

i was about to write to you about banh bo. I bought a pkt of premix and followed the instructions on the pkt but i left it to proof more hours than suggested. What turned out - no honeycomb but pretty good textured fatt koh.

On 6:15 AM , lilyng said...


the color is so vibrant. will give this recipe a go.

On 12:38 AM , Anonymous said...

How to prepare the "Com RuQu"?

On 7:12 PM , Anonymous said...

Hi TT,
Glad to see you posting again. I have learnt so much about Vietnam and Vietnamese cooking from your blog. Thank you again.
I found a packet of netted spring roll wrappers - looks interesting but have no recipes to show how to use it. Do you dampen it first??? Thanks
PutuPiring from KC

On 11:17 PM , hoangtam/tt said...


I think what you bought is "banh re".

They're used to make egg rolls. The filling and method for wrapping is the same as regular egg rolls.

As for the wrappers...if you got the 'fresh' kind then just use them as you would with regular egg roll wrappers. If they're a bit dry then you'll have to mist the wrappers with squirt bottle to make it pliable in order to use it. Or, you can sandwich the wrappers between moist towels (I prefer the misting method).

On 7:57 AM , Anonymous said...

Thanks for your help tt

On 3:21 PM , Beau Lotus 涟 said...

So glad that you are posting again and with this beautiful purple Fatt Koh!

I have been meaning to make some myself, so this recipe will come in handy. Thanks for sharing!

And do let us know what you've been up to!

Lovely old recipe book, by the way. I love all things old and have taken over some of my mom's recipe books though for some reason they only date from the 80s.

On 12:51 PM , Wandering Chopsticks said...

These are so gorgeous! I'm going to have to try them soon. I have a few Vietnamese cookbooks I got from my mom too that I've been meaning to thumb through.

It's nice to see you blogging again.

On 1:18 AM , Brightclouds said...

Quyển sách của bạn thật là cũ xưa ! Chiếc bánh như từ quá khứ bước ra .. vẫn mới tinh.

On 5:28 PM , Anonymous said...

There is a similar dish in my mothers country called Puto, and sometimes ube (what you call khoai mỡ) is used in this as well. Puto uses lye water and/or yeast to get the same basic chemical effect although the yam is usually used in powdered form like I had a viet flatmate ages ago (circa 1991-94) and she'd often make these at her parents and bring them to the flat and I'd get some puto so we could compare the Pinoy versus Viet versions of things.

On 10:58 AM , Anonymous said...

I'm a little confused. The recipe says to add in the fermented rice, yet the ingredients does not say fermented rice; it says com ruou. So, by that do you mean just the wine part of it, or do you mean the actual wine with the rice still in it?
Great blog by the way, your recipe for banh bo nuong chay is the best, I make it often; I'm not vietnamese and all my Viet friends say I make it better than they do :)

On 11:48 PM , hoangtam/tt said...

Com Ruou is Vietnamese for fermented rice. Use the rice and the wine.

On 1:46 AM , Anonymous said...

Chị cho em hỏi lượng phèn chua cho vào khoảng bao nhiêu vậy chị? Bánh chị làm nhìn ngon quá trời luôn.

On 1:28 AM , hoangtam/tt said...

Đây là "Anh" chứ không phải Chị đấu nhé.

Phèn giúp làm bánh dai, chỉ cần một chút chừng 1/8 muỗng cafe (một pinch)là đủ nhiều phèn quá thì bánh sẽ ít nở bông khi hấp.