In a large bowl, combine together milk, salt, sugar, oil, and instant yeast. Add the sifted glutinous rice flour and all-purpose flour into the mixture and mix with a wooden spatula until well combined.

Cover the bowl and rest the dough for 1 hour at warm temperature or until doubled.

Mix the dough with a wooden spatula until the gas is released. Cover the bowl and rest the dough again for 20 minutes at a warm temperature.

Grease your hands lightly with vegetable oil. Take a handful of dough with your hands. Flatten and spread the dough. Add 1 ½ tablespoons of cheese filling onto it. Gather the edges and seal the dough. Repeat with the remaining dough.

Preheat a non-stick frying pan on medium heat and add a thin layer of vegetable oil.

Once the oil is heated, place one dough onto the frying pan, the sealed part down. Cook for 25-30 seconds or until the bottom is light golden brown. Flip and press the dough with a spatula or hotteok hand presser until flat and thin. Cook until the bottom is golden brown for about 1 minute. Flip the dough again and cook for about 1 more minute to let the cheese filling fully melt.

Transfer the cooked hotteok to the paper-lined plate to remove the excess oil. Serve hot.