- Blanch the chives in boiling water, about 10 seconds. Quickly cool in ice water. Drain and set aside.
- In a saucepan, bring the broth to a boil with the leek, garlic, and thyme. Cover and simmer gently for about 15 minutes. Season with salt and pepper. Strain the broth through a sieve. Keep warm.
- Peel and cut the carrots into ½-cm (1/4-inch) thick slices.
- With the tip of a bamboo stick, pierce the carrot slices to mimic buttons. Thread the chives through the holes and tie the strands. If desired, cut the sprigs that stick out.
- Place the buttons in the broth and simmer for about 5 minutes. Serve the soup into bowls.