Steps

1. In a pot, combine dashi stock 400cc, soy sauce 5 tbsp, mirin (sweet rice wine) 5 tbsp, and sugar 1.5 tbsp, and bring to a boil over high heat. Once boiling, turn off the heat. (Key Tip! The basic ratio for mentsuyu is 5 parts dashi to 1 part each of soy sauce and mirin. Today, we're adding sugar to make it slightly sweeter since we're including meat. Boiling once helps to evaporate the alcohol from the mirin and meld the flavors.)
   🕒 00:58
2. Turn off the heat and add chili oil (to your liking) to the pot, stir to combine, and chill in the refrigerator.
   🕒 01:54
3. In a separate pot, combine cooking sake (rice wine) 3 tbsp, mirin (sweet rice wine) 3 tbsp, soy sauce 3 tbsp, sugar 3 tbsp, and grated ginger 1 tbsp. Mix well.
   🕒 02:13
4. Add beef slices 250g to the pot and cook over medium heat, breaking them apart. Reduce heat to low and simmer for about 5 minutes. Once cooked, turn off the heat and let it cool to room temperature. (Key Tip! Cooking the meat in cold broth results in a tender texture. Avoid overcooking, as it will become tough, so turn off the heat as soon as the meat is cooked.)
   🕒 02:36
5. Thinly slice 1 green onion stalk diagonally (sasagaki style).
   🕒 03:12
6. Soak the thinly sliced green onions in water for about 5 minutes, then drain. (Key Tip! Soaking in water removes the sharp bite of the green onions, making them crisp. However, soaking for too long will remove too much of the flavor, so aim for about 5 minutes.)
   🕒 03:38
7. Remove the bands from 3 portions of somen noodles. (Key Tip! Removing the bands before boiling allows for smoother and less rushed cooking when adding them to the pot.)
   🕒 03:54
8. Boil the somen noodles in plenty of boiling water according to the package instructions. (Key Tip! To prevent the noodles from sticking and to maintain the water temperature, boil them in a generous amount of water.)
   🕒 04:10
9. Once the somen noodles have softened during boiling, gently separate them to prevent sticking.
   🕒 04:36
10. Drain the boiled somen noodles, then rinse them thoroughly under running water. (Key Tip! Since oil is used in the somen production process, rinsing well removes the oil, resulting in a clean and chewy texture.)
    🕒 04:54
11. Once the rinsed noodles have cooled, immerse them in ice water to chill thoroughly, then drain well and place in serving bowls. (Key Tip! Putting them directly into ice water will cause the ice to melt quickly. For efficiency, chill the noodles first and then place them in ice water once they've cooled down.)
    🕒 05:26
12. Arrange the cooled braised beef on top of the somen noodles in the serving bowls.
    🕒 05:55
13. Top with the drained green onions and a generous amount of shredded nori (seaweed) (to taste).
    🕒 06:04
14. Pour the chilled spicy chili oil mentsuyu into a separate bowl.
    🕒 06:27
15. Crack 2 eggs into the mentsuyu bowl and sprinkle with white sesame seeds 1 tbsp. (Key Tip! Stirring in the egg when serving will create a mellow flavor.)
    🕒 06:38