If using fresh pumpkin, remove the skin and cut it into small pieces. (Cutting it into small pieces will make it easier to mash and faster to steam rather than bigger or whole pieces.)
Wash and clean the pumpkin.
Steam the pumpkin until it is soft enough to mash with a fork.
Then, mash the pumpkin using a fork and mix in the sugar to create a smooth puree.(The sugar helps bring out the moisture. However, if you think the pumpkin is too dry, you can add a little bit of water to make it more moist. Add 1 tablespoon of water at a time until you get the desired moisture.)
After mashing, mix in the glutinous rice flour and cornstarch to form a dough. (I suggest adding the glutinous rice flour and cornstarch gradually since the pumpkin moisture may vary depending on what you are using. Generally, the dough is sticky to touch at first, but then it should become smooth to the touch without sticking to your hands.)
Once you form a whole circular dough, take a small portion and make a flat circle by rolling it into a small ball and flattening it.(I recommend doing this against a non-stick work surface, such as a baking tray.)
Then, place the red bean paste at the center and wrap it to form a circle.(It is best if the filling is also rolled into a small ball to make it easier to create a round ball with the dough.)
Seal the dough by pinching the edges.
Next, form a ball by rolling it between your hands.
When you have a round ball, create pumpkin-like curves using a toothpick or a fork.
Decorate the top of the pumpkin cake with short green celery stalks.
Lastly, place it back in the steamer with boiled water and steam on high heat for 20 minutes.
Enjoy the sweet and soft little pumpkins at any time of the day!