Gather all the ingredients.

Bring a large pot of water to a boil for the udon noodles. Once boiling, keep it covered on low heat until you‘re ready to cook the noodles.

To make the broth from scratch, make 2½ cups dashi of your choice.

In a medium saucepan, add 2½ cups or 600 ml water and 1 dashi packet. Bring it to a boil over medium heat. Simmer for 2–3 minutes. Then, squeeze the liquid from the dashi packet and discard the packet.

Add 1½ Tbsp soy sauce, 1 Tbsp mirin, 1 tsp sugar, and ⅛ tsp Diamond Crystal kosher salt and mix it all together. Cover the pot with a lid to prevent evaporation and keep it hot. Remove it from the heat and set aside.

Cut the white part of ½ Tokyo negi diagonally into ½-inch slices. Set aside.

Thinly slice the leaves and tender stems of 4 sprigs mitsuba (optional). Cut 1 green onion/scallion into thin slices. Transfer the green onion slices and mitsuba to a small plate or bowl for topping the soup later.

Diagonally cut 4 slices narutomaki. Then, cut 6–8 oz thinly sliced beef in half.

Heat the frying pan on medium heat. When it‘s hot, add 1 Tbsp neutral oil and the Tokyo negi. Sauté the negi until golden brown and tender.

Add the meat and cook until it‘s no longer pink. Add 2 tsp sugar and 1 Tbsp soy sauce. Stir-fry the meat until it is well coated with the seasoning. Remove from the heat.

Cook 2 servings udon noodles in boiling water according to the package instructions. Drain well and rinse quickly with water to remove the excess starch.

Divide the well-drained udon noodles into individual serving bowls and pour the hot broth over the noodles to cover.

Place the stir-fried beef, narutomaki, green onions, and mitsuba on top. If you like it spicy, sprinkle shichimi togarashi on top.