Rinse the mochi rice and drain the excess water in a sieve.
Place the washed adzuki beans in a pot, pour water until the beans are covered completely, and turn on the heat (there's no need to soak the adzuki beans beforehand, start cooking the beans as-is).
Once the water comes to a boil, cook them for 2-3 minutes, and strain to get rid of the scum.
Return the adzuki beans to the pot, add 800 ml of fresh water, and turn on the heat. When it comes to a boil, turn down the heat to low, cover with a lid, and simmer for about 30 minutes.
Once the adzuki beans become tender enough that they can be easily crushed between your fingers, separate the adzuki beans from the water they were boiled in.
Cover the adzuki beans with plastic wrap to prevent them from drying out.
Expose the boiled water (that the adzuki beans were boiled in) to air and promote oxidization by scooping up the water with a ladle and pouring it back into the bowl from a high place.
When the boiled water cools down, put the glutinous rice in the rice cooker, and pour in the boiled water until it reaches the 3-cup line for okowa. Add salt and the adzuki beans and let it sit for about 30 minutes.
Once it's finished cooking, loosen up the rice and mix well. Serve it up with black sesame seeds and salt (gomashio) on top.
Story Behind this Recipe
I made this for my son's okuizome (weaning ceremony) Since I didn't have a large steamer, my mom taught me how to cook sekihan using the rice cooker. It turned out to be great, so I decided to post this recipe for future reference.
By exposing the boiled water (that the adzuki beans were boiled in) to air, this will promote oxidization and the red color of the sekihan will be more vibrant.
After pouring the boiled water into the rice cooker until it reaches the 3-cup line for okowa, you should still have some leftover boiled water! Instead of adding all of the boiled water to the rice cooker, adjust the amount until it hits the 3-cup line.