Bring 4 cups of low-sodium vegetable broth to a boil over medium-high heat.
Lower the heat and add garlic, ginger, carrots, mushrooms, celery, and bok choy. Let the soup simmer for 6-8 minutes until the bok choy is tender.
Stir in soy sauce and season with salt and pepper to taste. Drizzle sesame oil over the soup and garnish with chopped cilantro and green onion.