In a small bowl, dissolve the sugar in warm water. Sprinkle the yeast over the water and let it sit for about 5 minutes until it becomes frothy.

In a large mixing bowl, combine the flour and salt. Make a well in the center and pour in the yeast mixture and vegetable oil. Mix until a dough forms.

Knead the dough on a lightly floured surface for about 10 minutes until it becomes smooth and elastic. Place the dough in a greased bowl, cover with a damp towel, and let it rise in a warm place for about 1 hour or until doubled in size.

Divide the dough into 4 equal portions. Roll each portion into a ball and then flatten it into a small circle. Place a spoonful of red bean paste in the center of each circle. Seal the edges and shape into a smooth bun.

Place the buns on a baking sheet lined with parchment paper. Cover with a damp towel and let them rise for another 30 minutes.

Preheat the oven to 350°F (180°C). Bake the buns for about 15-20 minutes or until they are golden brown.

Let the red bean paste buns cool slightly before serving. Enjoy!