Parboil the bean sprouts in salted water, drain, and let cool. Mix with the ra-yu. Soft boil the egg.
Add 50 ml water and the katakuriko slurry to the meat miso to thicken. Boil the noodles, coat in the sesame oil, and transfer to a dish.
Top the noodles with the soft-boiled egg cut in half, the lettuce, bean sprouts, and meat miso.
Homemade Tianmianjiang (Chinese sweet flour paste)