Salted Egg Yolk Lava Bun (Liu Sha Bao)

I discovered liu sha bao (流沙包) or salted egg yolk lava bun many years ago at a dim sum restaurant in Daly City, California. John's dad, who grew up in Hong Kong, enjoys taking over the ordering at Chinese restaurants. We always end up with more than we can consume in one sitting, but I love watching him order off the menu or ask for specific things. He usually orders various steamed dessert dumplings for dessert, and that's how I discovered liu sha bao.

Developing this salted egg yolk bun recipe has been a journey for me. Ever since I had my first bite of liu sha bao, I knew I wanted to try to make this steamy golden egg yolk bun at home one day. Well, that day finally came, which quickly turned into multiple days, and eventually numerous weeks of experimentation. I sought to ensure the center filling was consistently runny when I opened the bun. The recipes I found seemed straightforward enough, but there are nuances to account for, such as the melting point of the butter that you use or how long you steam the buns. 

The process is meticulous but worth it because it ensures a gooey lava-like texture when you make it. I just know that you will impress everyone who tries these egg yolk buns! Click here to go straight to those steps with tips.

What is Salted Egg Yolk Lava Bun?

This bun is a relatively newer dim sum creation, first introduced in Hong Kong in 2009. Salted egg yolk lava bun or liu sha bao holds a flowing surprise inside its fluffy white walls. Liu sha means "quicksand", and bao refers to baozi (包子), the term for steamed buns. This equates to “quicksand bun”, which perfectly describes what happens when opening one of these buns. It is always fun to watch the yellow egg yolk filling slowly dribble out of the bun as you gently tear down the middle.

Liu Sha Bao vs. Nai Wong Bao

Now that liu sha bao exists, we must not mistake it for the ever-popular nai wong bao (奶黄包 - egg custard bun). Nai wong bao is the more familiar dim sum dessert bun of the two. A set custard fills this sweet white bun instead of the runny center of liu sha bao.

A liu sha bao (salted egg yolk lava bun) filling will flow, and you must be careful when eating it. The golden filling is hot and may burn you if opened too soon after steaming. Additionally, the highlight ingredient of liu sha bao is salted egg yolk. The savory flavor of salted egg yolk combined with the milk sugar mixture makes the taste of liu sha bao more complex. 

How to Make Salted Egg Yolk

You can make salted egg yolks at home! Simply put egg yolks in a bed of salt. Then cover the yolks with more salt and put them in the fridge for 1 - 2 days. After your desired time, remove the eggs yolks and wash them gently with cold water. Salted egg yolks have long been a staple in various Asian households such as China and the Philippines. I typically make this quick version when I want to use salted egg yolks that do not require the yolk in its spherical form. 

If you want your egg yolks to be saltier, prepare the yolk two days ahead, so it has more time to rest in the salt. I suggest making a few because, from my experience, it takes a few tries to get the filling to gush out just right.

My Trial And Error in Making the Filling Flow

When I first decided to try making liu sha bao a few years ago, it was satisfying enough for me to see the filling slightly jiggle to establish that it wasn't custard. Fast forward to now, when I watch other recipe videos of liu sha bao I notice the filling nowadays is runnier and runnier, with a slicker texture. Since this is a recent dim sum creation, restaurants worldwide are more flexible in their variations. Not to mention, the runny and smooth version makes for an awesome Instagram-worthy picture and a fun experience ripping open a bun filled with golden salted egg yolk goodness!

Vital Salted Egg Yolk Recipe Tips

So I decided to make a runnier liu sha bao than the original viscous texture I first encountered. The common way to make it with room temperature butter may not work for you. It took me over thirteen attempts (yes, thirteen!) to make the filling runny. I learned a few crucial steps needed to guarantee the signature velvety salted egg yolk flow.

Melt Your Butter

Before doing anything else, as you gather your ingredients make sure to melt your butter in the microwave for 45 seconds on 50% strength. This will break down the large fat crystals, making the structure of the butter after this point easier to melt when you steam the buns. If you don't do this before making the filling and then cook the bun, the fat crystals will maintain the butter form. You could end up with a slightly loose custard consistency.

Use a Food Processor

After steaming the salted egg yolks, some recipes require you to smash them with the back of a knife to crush them into tiny pieces. Depending on your knife's weight and strength, this may or may not work. To get a smoother consistency:

1. Use a food processor to pulse the yolks before adding the rest of the ingredients.
2. Add the ingredients to the food processor to blend them together.
3. If you want to have that classic 'sand' texture, put aside a bit of pulsed egg yolk and fold it in after mixing the rest of the ingredients together. 

Do a 'Melt Test'

A melt test is the most crucial step to ensure a well-mixed liu sha bao filling with the right consistency you want in your bun. Place a heat-safe bowl in a pot of boiling water and place your liu sha bao mixture in the bowl. Mix until the filling melts to a thick liquid and check the consistency. Add more butter to the mix if you want it more fluid, or add more cornstarch to make it denser. When satisfied with the texture, remove it from the heat and cool on the counter. After it has cooled down, put a plastic cover on it and put it in the fridge to let it harden again for a few hours.

These steps were essential to my experience of making a successful liu sha bao. I repeated these steps multiple times, and it hasn't failed me yet! I hope it works just as well for you too. 

Use a Kitchen Scale

It is best to use a kitchen scale for this recipe. Measuring the ingredients as precisely as possible will help you achieve a flowy filling and fluffy bun. The resulting consistency is very sensitive to even slight changes in ingredient ratios. For example, adding just a few more millimeters of milk to my recipe ruined my egg yolk filling.

Don't Get Discouraged With Each Attempt

Though I am rooting for you to get this recipe right on the first try, it may take several trials to achieve that flowy filling. But don't give up on yourself! Over time, you will feel the type of consistency you should aim for during the melt test. You will also notice that your steam time may differ from the recipe. 

Ensure a Fluffy Bun

The fluffy white bun is part of the magnificent experience of the salted egg yolk bun! Consider the following tips for creating a soft, airy bun for your liu sha bao.

1. Use warm water for your dough. Turn off the heat when you boil water and wait 3 minutes before adding it to your dough.
2. Use your hands. This is the part where you can let people know you made these buns with love. 
3. Knead for eight minutes straight. As soon as you finish kneading, break the dough into pieces. 
4. Flatten the dough with a rolling pin. This will release bubbles and create a smooth surface.
5. When proofing, cover the dough to avoid dry, cracked skin.

Tips For Cooking Egg Yolk Buns

To steam the buns, boil water in a pot and place the steamer with the buns on top. Turn on your timer and set it to 5 minutes. After 5 minutes, immediately remove it from the pot and leave it on the counter to rest for 2 minutes. Allowing the steamer to rest before opening it will help ensure your buns are fluffy and prevent overcooking or curdling the filling.

How to Store Egg Yolk Buns

These buns have stayed in our fridge for a week. After steaming the buns, I let them cool completely and put them in a plastic container with a lid for storage in the refrigerator. When we want something sweet throughout the week, we just steam the buns again to get our sugar fix. The filling becomes less flowy over time, so the buns are best eaten fresh.

More Sweet Cantonese Food

If you have a sweet tooth, try pairing these buns with Hong Kong style milk tea! Another great steamed bun to try are black sesame seed buns.