Adapted from Maangchi.
For regular hotteok, omit the apples and lemon juice, and increase the nuts (if you like) by a few more tablespoons.
Many recipes I came across called for one part sweet rice (mochiko) flour to create a chewier, crispier hotteok; many others also called for milk. I actually found a plain AP flour and water version was nice and crisp on the outside but pleasantly chewy inside, without the slightly gummy, dense kind of chewy you get from mochi, and I liked that best. If you love mochi, though, you might find you prefer the sweet rice flour version — in that case, substitute half the all-purpose flour by weight for mochiko flour, and use 1 cup all-purpose flour and about 3/4 cup mochiko flour instead of 2 cups all-purpose.
On the use of milk, I was also surprised to find that I preferred the water version over milk, since I’ve really liked milk in the past for its ability to create a more tender crumb. Maybe it’s the fact that you want these to have a little bit of a chewy pull, but I found that the version with water was both softer and more pliable, with a satisfying chew.
Finally, I left the apples uncooked before frying but diced them fairly small, so that they were partially cooked when the hotteok were done. I liked that it left a bit of crunch, but if you’d like softer apples, I’d recommend sauteing the diced apples for a minute or two in just a bit of oil, letting it cool briefly, then mixing it with the brown sugar, cinnamon, and nuts.