Gather all the ingredients. Quickly rinse the green peas. Rinse the rice and drain well (click here to see the proper way to rinse rice).
In a medium saucepan, bring 2 cups (480 ml) water to boil and add ½ tsp kosher salt.
Add green peas and cook for 4 minutes, or until the peas are firm but tender (eat one and you’ll see). Remove from the heat and let the peas cool in the cooking liquid. This will prevent from getting wrinkles.
Once the peas are cooled down, reserve 1 cup (240 ml) of cooking liquid.
In a rice cooker bowl, put rice that has been drained well. Then add 1 cup of the reserved liquid. Add water to the rice cooker’s 2 cup line. Add ½ Tbsp sake and ½ tsp kosher salt and mix well. Place the kombu on top and start cooking the rice. For my family's preference, I usually add extra water, so in the image, you see the water is at 2 ½ cup line.
Once the rice is done cooking, discard the kombu.
Now we’re ready to add peas. The peas will change color with the remaining heat. Therefore, I recommend NOT to keep the rice in the rice cooker for a longer time (no more than 2 hours). You have two choices: 1) you could add green peas to the portion you need, or 2) transfer the rice to an airtight container and store it, and serve it as you need.
Transfer the rice in airtight containers and close the lid to keep the moisture in. Let cool completely before storing the containers in the freezer (read my tutorial post).