In a small bowl, dissolve the yeast and 1 tablespoon of sugar in warm water. Let it rest for 5-10 minutes until frothy. This ensures the yeast is activated.

In a large mixing bowl, combine the flour, remaining sugar, and salt. Gradually pour in the yeast mixture and vegetable oil, mixing until a sticky dough forms.

Knead the dough lightly in the bowl for 2-3 minutes until smooth. Cover with plastic wrap and let it rise in a warm place for 1-2 hours, or until it doubles in size.

While the dough rises, mix the brown sugar, cinnamon, and chopped nuts in a small bowl. Add sesame seeds for a nuttier texture if desired. This classic filling is the heart of hotteok and where its warm, caramelized flavor comes from.

Once the dough has risen, punch it down to release any air. Divide the dough into 6-8 equal portions and shape each into a ball.

Flatten each ball into a disk, place a spoonful of filling in the center, and gather the edges to seal the filling inside. Roll the filled dough back into a ball, ensuring no gaps or leaks.

Heat a non-stick skillet over medium heat and add a generous amount of vegetable oil.

Place a dough ball in the skillet, seam side down, and cook for 1-2 minutes until the bottom is golden brown.

Flip the pancake, gently flatten it with a spatula, and reduce the heat to low. Cover the skillet with a lid and cook for 1-2 minutes to allow the filling to melt.

Flip it once more and cook uncovered for another 30 seconds to crisp up the exterior. Remove from the pan and repeat with the remaining dough balls.