Cup of Yum
1. Gather all the ingredients. Please note that 1½ cups (300 g, 2 rice cooker cups) of uncooked Japanese short-grain rice yield 4⅓ cups (660 g) of cooked white rice.
2. Rinse 1½ cups uncooked Japanese short-grain white rice until the water is almost clear. Soak in water for 30 minutes. Drain well in a fine-mesh sieve for 15 minutes.
3. Thinly slice ½ sweet onion. I cut the onion against the grain so the slices keep their shape and texture after they‘re cooked.
4. In a frying pan, heat 2 tsp neutral oil over medium heat. Add the onion and ⅛ tsp Diamond Crystal kosher salt and sauté the onion slices until they are tender.
5. Add 2 Tbsp mirin and 1 Tbsp soy sauce.
6. Continue to sauté until the sauce is thickened.
7. Add the drained rice into the inner pot of a rice cooker and pour in the sautéed onion, including the sauce.
8. Add the water up to the 2 cup line on the inner pot. Press Start to cook. If you have a “Mixed Rice” option, use it (see Notes below). 
9. When the rice is finished cooking, chop some mitsuba (Japanese parsley) into small pieces and fluff up the rice with a rice paddle. Serve the rice and garnish with mitsuba.

To Store

1. You can keep the leftovers in an airtight container and store in the refrigerator for up to 3 days or in the freezer for a month.