The beans and rice were easy to prepare. I soaked 1 cup of adzuki beans (twice what the original recipe called for) and 1 and 1/2 cups of sticky rice overnight, in separate bowls. The next day, I drained and rinsed the beans, then cooked them for about 20 minutes while I rinsed and washed the rice. When the beans had finished cooking, I drained them but reserved the cooking water. The rice and partially cooked beans then went into a larger pot, with about 2 cups of the reserved bean cooking water, and a dash of salt. Less than 20 minutes later, the rice and beans were done.
The gomashio (black sesame seeds with salt) is also easy to make, although I had to work through a couple kinks. I used a recipe for stovetop gomashio at Just Bento, which was written for people who have a kitchen scale. Since I don't have a kitchen scale, I spent a little time with on-line measurement equivalent tables and a calculator, and ultimately figured that the recipe called for about 7 tablespoons of black sesame seeds, 2 teaspoons of salt, and 1/2 cup of water. I decided to make a half batch, using 3.5 tablespoons of black sesame seeds, 1 teaspoon of salt, and 1/4 cup of water.
The recipe said to toast the black sesame seeds in a pan over medium-low heat until they popped, and then add in salt water and stir until the water evaporated. I was worried about burning the sesame seeds (since I couldn't tell by color whether they were toasting), and so I may have started out with too low a heat setting. However, after about 25 minutes and several increases in temperature -- to almost medium heat -- my sesame seeds still weren't popping. Out of frustration, I tasted a seed and found that it was nice and toasty. So, perhaps the seeds don't really have to pop? I added the salt water to the pan and was rewarded with a wonderful salty sesame smell. The water evaporated in just a couple of minutes, leaving me with tasty gomashio to sprinkle over my beans and rice.
Since the gomashio can take some time to prepare, I would definitely recommend making it in advance.