Please refer the pumpkin steamed kuih recipe here. However, you can try to reduce the amount of water depending on how moist is the mashed sweet potato that you have.
100gm glutinous rice flour
150gm all purpose flour
1 tspn yeast
100gm mashed purple sweet potato
150ml warm water
50ml cooking oil
* extra cooking oil for hand coating
*1 big banana leaf, run through hot water to soften the leaf then cut small
(1) combine everything into a big mixing bowl and knead till smooth
(2) once its done, divide dough into 50-55gm each and round it (coat your hand with cooking oil), then let it sit on banana leaf by flattened the dough between 2 leaves.
(3) next, let dough rest for an hour.
(5) finally, steamed dough for 10 minutes over high heat.