Soft-boil the eggs

• Boil the eggs for 6 minutes.
• Plunge them into an ice bath, then peel and set aside.

Make the broth

• Rinse the pot, then add the vegetable stock, tamari and mirin.
• Bring to a simmer, then set aside and keep warm.

Cook the noodles and bok choy

• Boil the udon noodles according to the package (frozen udon cooks in about 1 minute).
• If using, add the baby bok choy to the pot.
• Drain well.

Assemble the bowls

• Divide the noodles among the bowls.
• Ladle the hot broth over the noodles.
• Drizzle each bowl with sesame oil and add a knob of butter.

Finish and serve

• Halve the soft-boiled eggs and add them to the bowls.
• Top with scallions, plenty of cracked pepper and a spoonful of chili garlic sauce if you wish.