In a large mixing bowl, combine 2 cups flour, 1 tablespoon sugar, and 1/2 teaspoon salt.

In a separate bowl, warm the milk to about 110°F and dissolve the yeast in it. Let stand for 5 minutes until foamy.

Add the yeast mixture to the flour along with 1 tablespoon vegetable oil. Mix until a shaggy dough forms.

Knead the dough on a lightly floured surface for 8-10 minutes until smooth and elastic.

Place dough in an oiled bowl, cover with a damp towel, and let rise in a warm place for 60-75 minutes until doubled in size.

While dough rises, prepare the filling by mixing brown sugar, cinnamon, and chopped nuts in a small bowl.

Once risen, punch down the dough and divide into 8 equal portions. Roll each into a ball.

Flatten each ball into a 4-inch circle, place 2 tablespoons of filling in the center, then gather the edges and pinch to seal completely.

Gently flatten the filled dough ball into a disc about 1/2-inch thick.

Heat 1 tablespoon oil in a large skillet over medium heat.

Place 2-3 hotteok in the skillet and cook for 3-4 minutes until golden brown on the bottom.

Flip and cook another 3-4 minutes on the other side, pressing gently with a spatula to flatten slightly.

Remove from skillet and let cool for 2-3 minutes before serving. The filling will be extremely hot.

Repeat with remaining hotteok, adding more oil to the skillet as needed.