In a medium saucepan, add 2⅓ cups dashi (Japanese soup stock), 1 Tbsp mirin, 1 tsp sugar, 1½ Tbsp soy sauce, and ⅛ tsp Diamond Crystal kosher salt.

Bring the broth to a gentle simmer. Once simmering, remove the pot from the heat. Cover with a lid and set aside.

Follow the instructions on your bottle of concentrated mentsuyu for the correct dilution ratio for noodle soup broth (shown here as めんのかけつゆ).

Combine the water, mentsuyu, and mirin in a medium saucepan. 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.

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. The brand of frozen udon noodles I use 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, drain them in a colander or scoop them up with a fine-mesh strainer. Serve the hot udon noodles in individual bowls.

Pour the hot broth over the noodles and top with thinly sliced green onion and shichimi togarashi for a spicy kick (optional). For a more substantial lunch or dinner, you can top it with tempura, beef, fish cake and toasted mochi, tofu, Inari age, or vegetables. Watch the video above for 4 variations!

You can keep the udon noodles and broth separately in airtight containers and store them in the refrigerator for up to 3 days.