Stir the sugar and yeast into the warm water in a large liquid measuring cup, then wait about 5 minutes. A foamy layer on top signals yeast activity.
Distribute the sweet rice flour evenly through the all purpose flour in a large mixing bowl. The dry mixture should look uniform before any liquid goes in.
Whisk the oil and salt into the yeast liquid, stir it into the flours with a wooden spoon, then cover with plastic wrap and let rise somewhere warm for about 3 hours or overnight in the refrigerator. The mixed dough should feel sticky and stretchy rather than firm enough to knead.
Reduce the roasted peanuts and sesame seeds to fine crumbs using a food processor, mortar and pestle, or a sealed zip-top bag and heavy pan. Stop while the mixture remains loose and crumbly, before it becomes a paste.
Combine the crumbs with the filling sugar, cinnamon, and salt, leaving out the salt if the nuts or seeds are salted. The finished filling should have evenly distributed cinnamon and no large, sharp nut pieces.
Pour enough neutral oil into a skillet to generously cover its bottom and heat over medium-high. A filled dough ball should sizzle on contact without immediately darkening.
Oil both palms generously, spread about 3 oz of dough across one palm, add 2 tablespoons of filling, and gather and pinch the edges closed. The filling should be fully enclosed, with no open seam or exposed sugar.
Set the sealed dough seam-side down in the skillet, leave it undisturbed for about 30 seconds, then flatten with an oiled press or spatula and fry for another 1–2 minutes. The underside should turn crisp and golden, with enough space around each pancake to expand when pressed.
Turn the pancake carefully and continue frying until the second side develops a crisp golden crust. Both surfaces should have similar coloring rather than pale patches or scorched spots.
Lift the cooked pancake onto a cooling rack or a paper towel-lined plate, then continue shaping and frying the remaining dough in batches of about 2–3 as your skillet allows. The exterior should remain crisp as excess oil drains away.