In a medium pan add water, instant dashi powder, soy sauce, sugar, mirin, and tsuyu. Then bring to a simmer over medium heat for about 2-3 minutes.
Once the broth has begun simmering add the udon noodles directly into the hot broth. Use a spoon to gently loosen the noodles and cook for 1-3 minutes until the noodles have softened.
Transfer to a large bowl, then garnish with green onion, furikake seaweed seasoning, fried bean curd, and narutomaki (fishcake). Serve and enjoy!