Dduk (tteok) is not exactly a dessert, since Koreans really don't eat dessert. It is a sweet that is served for special occasions, like birthdays, or other celebrations. This is a variation of dduk (tteok) or Korean rice cake that is like Japanese mochi, using glutinous rice flour (chapssal) and red beans, rolled into a small chewy ball. For a version that is more like a cake, try this recipe for chapssal dduk.
3 cups red beans, also called azuki beans, (pat 팥)
2 cup sugar
1 tsp salt
3 cup sweet rice flour (chapssalgaru 찹쌀가루)
1 tsp salt
2 cup water
Soak red bean for 2-3 hours, and cook until very tender. Grind it in a blender, add sugar and salt.
Put cooked bean paste on a frying pan and heat slowly, stirring frequently so that the water evaporates and the beans become fluffy. Remove from heat; put the mixture in a bowl for later use.
Mix rice flour with salt. Mix in water slowly, forming a rice flour batter.
Spread a cheesecloth over a steamer, place in pot. Bring the water to a boil; when steam comes out, spread the rice mixture on the cheesecloth and cook covered for 15-20 min. When the batter looks clear, not murky, it's done.
Dust a large cutting board or plastic workspace with cornstarch. This will be your working area. Dump out the cooked rice mixture onto the workspace, peeling off the cheesecloth. Use corn starch flour on your hands to make it easier to handle, and knead the dough a little bit so that the consistency is even. You can roll it into a large tube, then experiment with slicing off the right amount of rice flour dough for your dduk (about 1"). With one piece of dough, roughly flatten into a curved disc. Put a scoop of red bean filling (about 1 - 2 tsp) in the middle, then roll the edges around the filling. Pinch close and roll so that it is a nice round ball with your hands. Dust with more cornstarch if necessary and set aside.