Activate the yeast. In a bowl, combine warm milk, yeast, and sugar.
Stir and let it sit for 5–8 minutes until foamy. If it doesn’t foam, your yeast may be inactive or the liquid too hot or cold.
Mix the dough. Add flour, salt, and 1 tablespoon oil to the yeast mixture. Stir with a spoon until a sticky dough forms.
It will be soft and slightly tacky—this is good.
First rest (rise). Cover the bowl with plastic wrap or a damp towel. Let it rise in a warm spot for 45–60 minutes, until roughly doubled.
Make the filling. In a small bowl, mix brown sugar, cinnamon, chopped nuts, and a pinch of salt. Set aside.
Degas and chill (optional but helpful). Stir the dough to deflate it.
For easier shaping, refrigerate for 15–20 minutes. This step firms the dough slightly and reduces stickiness.
Portion the dough. Lightly oil your hands. Divide the dough into 6–8 balls, depending on your pan size and how thick you like them.
Fill the dough balls. Flatten one ball into a small disk in your hand.
Add 1–1.5 tablespoons of filling to the center. Carefully pinch the edges together to seal, forming a smooth ball. Make sure there are no gaps.
Preheat the pan. Heat a large nonstick skillet over medium heat.
Add enough oil to lightly coat the bottom.
Cook and press. Place a filled dough ball seam-side down in the pan. Let it cook for 30–45 seconds, then gently press it down with a spatula to form a pancake, about 4–5 inches wide.
Brown both sides. Cook 2–3 minutes until the bottom is golden. Flip, press again lightly, and cook another 2–3 minutes.
If it browns too fast, lower the heat; if it’s pale, increase slightly.
Check for doneness. The hotteok should be deep golden with a slight crisp. The center will feel soft and filled. If unsure, lower heat and cook 1–2 more minutes to ensure the sugar fully melts.
Repeat. Cook remaining hotteok, adding a bit more oil as needed.
Keep cooked hotteok on a wire rack so they stay crisp.
Serve warm. Let them cool for 1–2 minutes before biting—hot sugar can burn. Enjoy plain or with a cup of tea or coffee.