In a mixing bowl, add yeast, flour, and warm water.

Stir well until you form chunks of dough.

Then, knead into a smooth dough.

Roll the dough into a cylindrical shape and cut it into 7 equal portions using a dough cutter or knife.

Afterward, knead each piece into a rough ball of dough and set aside.

Meanwhile, make the filling with flour, sesame seeds, and brown sugar.

Mix the filling thoroughly.

Next, take the balls of dough and roll them into flat circular dough wrappers using a rolling pin.

Then, wipe some water on the edges of the wrapper.

Add the sugar filling and shape it into a triangle.

To make a triangle, take three corners of the wrapper and firmly press them to the middle. The three corners should meet at the center of the wrapper.

Pinch the edges firmly to seal.

Place the triangular buns in the steamer basket lined with parchment paper.

Add some warm water to the steamer and proof the buns in warm water for 15 minutes. Make sure it is covered with a lid.

Next, steam the buns for 12 minutes in boiling water.

Turn off the heat and refrain from opening the steamer lid. Allow the buns to rest undisturbed for 5 minutes.

Eat while it's hot and enjoy a fragrant and chewy sugar bun.