Kitsune Udon is a Japanese noodle soup in dashi broth, topped with seasoned fried tofu, pink-swirl narutomaki fish cake, and scallions. This hearty udon soup is one of the most popular, classic Japanese noodle dishes.
Gather all the ingredients. Before we start: It's really important to have good flavorful dashi for this recipe. Although you can take the shortcut by using dashi powder or dashi packet, I encourage you to make your own dashi because the broth tastes so much better! It only takes less than 30 minutes to make. For vegetarian/vegan, please use Kombu Dashi.
To Make Homemade Dashi (Please skip if you already have dashi)
Put the kombu and 2 ½ cup water in a measuring cup for at least 30 minutes. If you have time, soak for 3 hours or up to half a day. Kombu’s flavor comes out naturally from soaking in water. If you don’t have time at all, skip soaking.
Transfer kombu and water to a saucepan. Slowly bring to a boil over medium-low heat.
Just before boiling (you will see bubbles around the edges of the pan), remove the kombu. If you leave the kombu inside, the dashi will become slimy and bitter. Now this broth is Kombu Dashi (vegetarian/vegan) and it's ready to make udon soup. For non-vegetarian/vegan, add 1 ½ cups katsuobushi and bring it to a boil again.
Once the dashi is boiling, reduce the heat, simmer for just 15 seconds, and turn off the heat. Let the katsuobushi sink to the bottom, about 10-15 minutes. Strain the dashi through a fine-mesh sieve set over a saucepan. Now you have roughly 2 ¼ cup dashi.
To Make Udon Soup
In a saucepan, add the dashi, 1 Tbsp mirin, 1 tsp sugar, 1 Tbsp soy sauce, and ½ tsp kosher salt and bring to boil. Once boiling, turn off the heat or cover and keep on a low simmer.
To Prepare Toppings
Squeeze excess liquid from the inariage (or you can keep it as it is). Cut the green onion into thin slices. Slice the Narutomaki fish cake into 1/8 inch (3 mm).
To Prepare Udon Noodles
Bring a large pot of water to boil for udon noodles. My favorite udon is the frozen Sanuki Udon. Cook the frozen udon noodles in boiling water for 1 minute (no need to defrost). If you use dry noodles, follow the package instructions.
Pick up the noodles in a strainer or drain the hot water. Make sure to remove excess water (which will end up diluting your soup).
Serve udon noodles and hot soup in serving bowls and top with inariage, narutomaki, green onion and sprinkles of shichimi togarashi.