Warm oil in a large pot over medium heat. Add onion, carrots, and celery and cook for 6 to 8 minutes, stirring occasionally.
Stir in garlic and ginger and cook for 1 minute.
Pour in broth and bring to a gentle boil.
Reduce heat and simmer for 20 to 25 minutes, until the vegetables are tender.
Stir in shredded chicken and cooked rice, if using. Simmer for 5 to 10 minutes, until warmed through.
Stir in spinach or greens, if using, and cook until just wilted.
Add lemon juice, salt, and pepper to taste. Serve warm with herbs, egg, or other toppings if desired.