Award-winning chef Takashi Yagihashi shows Martha how to make his favorite noodle dish, natto soba.
Bring a large pot of water to a boil. Prepare an ice-water bath and set aside. Place noodles in a fine-mesh strainer and submerge in boiling water. Cook for 1 minute if using fresh noodles, 4 to 5 if using dried. Remove noodles from boiling water and rinse under cold running water until water runs clear; submerge noodles in ice-water bath until cold; drain.
Divide noodles evenly between 4 bowls. In a circular formation, place small mounds of natto, nori, scallions, and katsubushi on top of noodles. Using a knife, carefully cut the top of each quail egg and pour egg into center of circular formation. Serve with cups of cold broth on the side.
To eat, pour broth over noodles and mix all ingredients together with chopsticks until egg is well combined.
Note: Raw eggs should not be used in food prepared for pregnant women, babies, young children, or anyone whose health is compromised.