These irresistible molten steamed egg custard buns, or liu sha bao, are an instant crowd-pleaser. It is impossible to say no to these pillowy soft steamed buns bursting with buttery sweet and salty egg custard.
Whenever I go to dim sum, I always HAVE to order these molten steamed egg custard buns. I go so far as to search through all the yelp review photos to make sure the restaurant makes these buns before I go eat there. Simply put, these gooey golden sweet and salty egg custard wrapped in pillowy soft buns are pure culinary magic. Now you can have these magical treats right at home. I have broken down all the steps for you below. Let's get started!
What are Steamed Egg Custard Buns or Liu Sha Bao?
Steamed egg custard buns are called 黃金流沙包 or Liu Sha Bao in Chinese. Liu Sha literally means quicksand. Liu sha bao means that the filling flows out like molten lava. The delicious sweet and salty filling is made with butter, salted egg yolks, milk powder, custard powder, evaporated milk, and sugar. Served warm, the filling oozes out with your first bite and you instantly will taste molten egg custard bun heaven.
Ingredients For The Custard Filling
- Salted Egg Yolks: salted egg yolks are traditionally cured duck eggs used in fillings for steamed buns, mooncakes, tossed in stir fry dishes, and many more. Steamed egg yolks can be found in any Asian grocery market in the eggs section or freezer section.
- Unsalted Butter: Since the custard is made up of very few ingredients, try to use the best quality ingredients for the best taste. I fully support using unsalted European butter, at room temperature. European butter has a higher fat quantity of at least 82 percent fat because it has been churned longer. European-style butter is my favorite because of its rich taste, softer texture, faster melt, and beautiful saturated yellow.
- Powdered Sugar: powdered sugar is necessary for the custard to easily melt without any graininess.
- Evaporated Milk: Evaporated milk has a richer and creamier consistency than regular milk. But if you don't have any evaporated milk available you can substitute it with whole fat milk. You can find evaporated milk here or in any grocery store in the baking aisle.
- Milk Powder: milk powder is also known as dehydrated milk. You will need milk powder for this recipe because it adds the creamy and richness of the milk without the added moisture which will make the custard too difficult to shape with your hands. You can find milk powder here or in any grocery store in the baking aisle.
- Custard Powder: Custard powder is made up of a combination of milk, sugar, and egg yolk. This is the main ingredient for that luxurious vanilla and sweet custard flavor. I used this custard powder or you can find it in any grocery store in the baking aisle.
Ingredients for the Buns
- Whole fat milk: Using full-fat whole milk is key to moisturizing the dough and binding it together.
- Instant or Active dry yeast: I normally use instant yeast but active dry yeast works just as well to leaven the dough.
- Granulated sugar: the sugar helps activate the yeast.
- All-purpose flour: combining all-purpose flour and wheat starch together forms that beautifully soft and pillow dough.
- Wheat starch: wheat starch is NOT the same as wheat flour. Wheat starch is what makes the dough soft. You can find wheat starch online here at any local Asian grocery market.
- Powdered sugar: powdered sugar adds that subtle sweetness to the bao dough.
- Baking powder: baking powder gives the dough its soft rise.
- Salt: the salt balances out the sugar.
- Vegetable shortening: vegetable shortening moisturizes and tenderizes the dough without too much moisture from milk.
- Large egg white: the egg white also contributes to the natural rise of the dough.
- Vegetable oil: the oil helps liquify the egg and also keeps the dough soft and prevents it from drying out.
- Lemon juice or lime juice: the smallest hint of lemon or lime juice activates the baking ammonium carbonate. You will not be able to taste the citrus.
- Baking ammonium bicarbonate: Ammonium bicarbonate is the ancestor of modern baking soda. It is a leavening agent that was used before baking powder or baking soda. When the ammonium bicarbonate is mixed with the lemon juice it is activated and creates a unique soft rise to the dough. You can buy baking ammonium bicarbonate here.
How to Make Steamed Molten Egg Custard Buns
I. Make the Custard Filling
- Prepare the salted egg yolks. Separate the egg yolks from the egg whites. Rinse the egg yolks in a bowl of water and drain. Place the egg yolks on a small plate in your steamer and steam on medium-high for 10 minutes.
- Mix the butter and powdered sugar. While the egg yolks are steaming, whisk the softened butter and powdered sugar until creamy.
- Add in the rest of the ingredients. Add the evaporated milk, milk powder, and custard powder and mix until incorporated.
- Smash the steamed egg yolks and fold them into the mixture. Once the egg yolks are done, smash the egg yolks into small pieces with a fork. Fold in the mashed egg yolks.
- Chill the mixture then form into balls. Place the custard mixture in the freezer for about 1 hour or the refrigerator for 3 hours or until the mixture has hardened. After the mixture has hardened, take the mixture out and form 1 inch balls on a parchment-lined baking tray or large plates. Place back in the freezer until the dough is ready.
II. Make the Dough
- Prepare the yeast. Warm the milk to 110 F degrees. Add the active dry yeast and granulated sugar. Cover with plastic wrap and let sit for 10 min.
- Sift the dry ingredients. Sift flour, wheat starch, powdered sugar, baking powder, and salt into the bowl of your stand mixer with a paddle attachment. Mix together on low.
- Add the shortening while the mixer is mixing on low. Make sure the shortening is broken up into small pieces by feeling it with your hand.
- Activate the ammonium carbonate with lemon juice. In a separate small bowl, combine lemon juice with baking ammonium carbonate. Let it fizzle for 5 min.
- Liquify the Egg in oil. In another separate bowl, combine the room temperature egg white with vegetable oil. Liquify the egg by pulling up the egg yolk with a fork a few times.
- Mix all the mixtures together. In the stand mixer on low with the paddle, mix the yeast milk mixture, then add the egg and oil mix, then lastly add the ammonia and lemon mix for 30 seconds.
- Switch to a dough hook and knead the dough. After 30 seconds, switch out for the dough hook and mix on level 2 speed for 2 minutes or until it forms into a ball in the mixer and is no longer sticking to the bowl. The dough should be tacky but not overly sticky. Take the dough out and gently knead the dough by hand for 1 minute. Form the dough into a ball and transfer it into a lightly greased large bowl.
- Proof the dough. Cover with plastic wrap and place in a warm area (100 F) for about 1-1.5 hours or until double in size
III. Shape and Steam Buns
- Divide and roll out the dough. Divide into 15 equal pieces and roll into smooth balls. Then, use a rolling pin and roll out the edges leaving a thicker center. Approximately 4-inches.
- Add the filling and form the bun. Add 1 tablespoon of filling and wrap the dough around the filling to form a ball. Then pinch to seal. You may need to remove the excess dough. Tightly pinch the dough so no holes remain!
- Let the buns rest. Place parchment squares or cupcake liners underneath and let buns rest for 15 minutes
- Steam the buns. Prepare steamer on the stove, bring the water to a boil then steam the buns 1-2 inches apart on medium-high for 10 minutes.
- Serve immediately when hot.
Tips for the Molten Egg Custard
- Use fresh salted eggs from the Asian grocery store for best-tasting results. If they're not available, then the vacuumed sealed salted egg yolks work as well.
- Cream the butter with the sugar before adding the other ingredients in. This is really important for that silky custard. Creaming the butter ahead of time will de-clump the mixture and form that creamy finish.
- Freeze the custard. Freezing the custard will firm the custard up making it easy to form into balls. After you form them into balls immediately place them back in the freezer so they hold their shape.
- Use a kitchen scale! Using a scale will always give you the best results guaranteed. I love my kitchen scale that I got on amazon.
- Use a stand mixer. The stand mixer will make kneading the dough so much easier. You can also knead this by hand but it will take about double the time.
Tips for the Bao Dough
- If the dough is too sticky, add 1 tablespoon of flour at a time until it becomes tacky and doesn't stick to the bowl.
- If the dough is too dry, add 1 tablespoon of warm water at a time until it reaches the tacky consistency. You don't want the dough to be too dry, the seam will not properly seal when you pinch if it is and the filling will ooze out during the steaming process.
- Roll out the edges of the dough when making the dough discs. The dough should be evenly distributed throughout and that means having thinner edges to pinch and a thicker fluffy center.
- Tightly pinch the dough together. Don't be afraid to really seal it together. I did not pay much attention to my pinching once and my buns exploded in the steamer.
- Make sure to rest the bao for 15 minutes after shaping. This is crucial for that slight rise and fluffiness in the bao. Careful not to wait too long because the yeast will overrise and create a gap between the dough and the filling
- Steam the dough over medium heat. If the steam is too hot there may be a chance that the filling will explode and burst out.
- If your bao is wrinkly after steaming, it probably means that either your steam was too hot or you steamed them for too long.
Storage and Reheating Instructions
Serve immediately from the steamer. But if you have leftovers, once the buns have cooled completely wrap them individually in plastic wrap and place them in the refrigerator for up to 3 days. You can also freeze them as well for up to 1 month, and make sure to completely thaw them before reheating. To reheat simply pop them in the microwave or re-steam them. If they have slightly dried out you can wrap them in a wet paper towel before microwaving them.