Boil the buckwheat noodles in boiling water, then rinse in cold water.
Drain the rinsed noodles in a strainer to remove excess water.
Blend boiled soybeans with water in a blender until smooth.
Strain the soybean blend through a fine sieve for a silky texture.
Place the noodles in a bowl and pour the soybean broth over them.
Garnish with cucumber, cherry tomatoes, boiled egg, or your favorite toppings.
Season with salt to taste as desired.