Classic Udon Noodle Soup (Kake Udon or Su Udon) is all about simplicity. Thick, chewy noodles and a delicate homemade broth deliver a hot bowl of comfort. Enjoy this vegan-adaptable soup as is or add tempura, fish cake, and vegetables for a more substantial meal.
In a medium saucepan, add 2⅓ cups dashi (Japanese soup stock), 1 Tbsp mirin, 1 tsp sugar, 1½ Tbsp soy sauce, and ⅛–¼ tsp Diamond Crystal kosher salt.
Bring the broth to a gentle simmer. Once the broth is simmering, remove it from the heat. Cover with a lid and set aside.
To Prepare the Quick Broth (with mentsuyu; optional)
Follow the instructions on your concentrated mentsuyu bottle for the correct mentsuyu-to-water dilution ratio for noodle soup broth (shown here as めんのかけつゆ).
In a medium saucepan, combine the water, mentsuyu and mirin. For the brand of mentsuyu that I use, I add 2⅓ cups water, ⅓ cup mentsuyu (concentrated noodle soup base), and 1 Tbsp mirin. Bring it to a simmer over medium heat. Once simmering, remove the pot from the heat. Cover with a lid and set aside.
To Cook the Udon Noodles
Bring a large pot of water to a boil. When the water comes to a full rolling boil, add 2 servings udon noodles and cook according to the package instructions. This brand of frozen udon noodles requires reheating them for 1 minute. Using chopsticks, stir the noodles to loosen them up. For fresh noodles, see the cooking instructions in my Homemade Udon Noodles recipe.
When the noodles are done cooking, drain them in a colander or pick them up with a fine-mesh strainer. Serve the hot udon noodles in individual bowls.