Preparation:

• To make the dough, dissolve 1 teaspoon of sugar and 1 teaspoon of dry yeast in 180 ml (¾ cup) of warm water. Let stand for about 10 minutes, until foamy.
• In a separate bowl, combine the flours and salt. Once the yeast mixture is bubbly, stir it into the flour mixture. The dough should be very soft, wet, and sticky—add up to 8 tablespoons of additional water if needed to achieve the right consistency.
• Cover and let rise at room temperature for about 3 hours, or until doubled in volume.
• Meanwhile, prepare the filling by mixing the sugar, cinnamon, and finely chopped walnuts.
• When the dough is ready, heat about 3 tablespoons of oil in a skillet over medium heat. Lightly oil your palms to prevent sticking. Scoop out a portion of dough the size of a gold ball and gently flatten it into a disc slightly larger than your palm. Place 1–2 teaspoons of the nut mixture in the center, then carefully gather the edges and seal to form a smooth dumpling.
• Place the hotteok in the pan with the side that rested in your palm facing up. Lightly oil a wide spatula and gently press it down until it reaches about 10 cm in diameter. Be careful not to tear the surface, or the filling may leak.
• Cook over medium heat for 3–4 minutes, until the bottom is golden brown. If it browns too quickly, reduce the heat. Flip and cook the other side until evenly browned and crispy.
• Repeat with the remaining dough and serve warm—allowing the molten filling to cool slightly before enjoying.