Combine the flour, yeast, water, sugar, and vegetable oil in a bowl. Mix, then knead on the table until the dough is smooth. Let it rest for 3 minutes.

Divide the dough into equal pieces and roll each into a round disc, making the center thicker and the edges thinner.

To make homemade red bean paste: Use 1 pound of red beans. Fill a rice cooker inner pot (for 10 servings) up to 80% full with water. Add 2 1/2 bowls of water to the outer pot. Cook, then drain the beans. Transfer to a skillet, mash into a paste, and cook until the water evaporates. Add 1/4 cup vegetable oil (about 60g) and 5 tablespoons sugar. Stir-fry until a slight crust forms on the bottom. Turn off the heat. The red bean paste will be soft at this point. Remove from the pan and let cool; it will firm up as it cools. Only use the paste once cooled.

Wrap the red bean paste in the dough and let the buns rise a second time.

Once risen, bring water to a boil and steam the buns over medium-high heat for 12 minutes.