In a large mixing bowl, combine the warm water, sugar, and active dry yeast. Stir and let it sit for about 5-10 minutes until frothy.
Add the flour, salt, and vegetable oil to the yeast mixture. Mix until a dough forms.
Knead the dough on a floured surface for about 5-10 minutes until it becomes smooth and elastic.
Place the dough in a lightly oiled bowl, cover with a clean cloth, and let it rise in a warm place for about 1-2 hours, or until it has doubled in size.
In a small bowl, mix together the brown sugar, chopped walnuts or peanuts, and ground cinnamon.
Punch down the risen dough and turn it out onto a floured surface.
Divide the dough into 8 equal pieces and shape each piece into a ball.
Flatten each ball into a disc and place a tablespoon of the filling in the center.
Gather the edges of the dough and pinch them together to seal, enclosing the filling completely.
Heat a non-stick skillet over medium heat and add a small amount of vegetable oil.
Place one of the filled dough balls into the skillet, seam side down.
Flatten the ball gently with a spatula until it is about 1/2 inch thick.
Cook for about 2-3 minutes on each side, or until the hotteok is golden brown and cooked through.
Remove the hotteok from the skillet and place it on a paper towel to drain any excess oil.
Repeat with the remaining dough balls.
Enjoy your meal!