Let the udon thaw out on a plate while you’re preparing the soup. In it’s frozen form, it’s typically already cooked and you just need to heat it through, so thawing it out will help it heat up faster in the broth.
While your udon is thawing, bring the dashi, soy, mirin, sake, and sugar (if using) up to a boil over medium heat. Add the chicken and simmer until it’s cooked through, about 2-3 minutes. Add the udon and simmer for 1 minute or until it’s heated through.
Put everything in a deep noodle bowl and top with green onions and enjoy with shichimi togarashi, if using.
Notes: You can find frozen udon in the freezer aisles of the Asian grocery store. You can also buy dashi at the Asian grocery store, or on amazon. Instant dashi is sold as granules and you just add them to water to create dashi stock.
