In a mixing bowl, combine warm water, sugar, and yeast. Let it sit until frothy.

Add flour and salt to the yeast mixture and knead until smooth.

Cover the dough and let it rise for about 1 hour.

Roll out the dough on a floured surface and cut into circles using a cookie cutter.

Place a spoonful of red bean paste in the center of each circle and fold over to seal.

Heat oil in a frying pan over medium heat.

Fry the donuts until golden brown on both sides.

Remove and drain on paper towels.