Heat a large pot over medium heat and add the olive oil and butter. Stir in the onion, carrots, salt and pepper, cooking until softened, about 3 minutes. Stir in the mushrooms and garlic, cooking until the mushrooms just soften, about 3 more minutes. Add the stock and bring the mixture to a boil.
Reduce to a simmer and cook covered for 10 minutes. Stir in the chicken and bok choy, simmering for 10 more minutes. Right before serving, toss in the green onions.
Serve with toppings of cilantro, toasted sesame oil, tamari, rice vinegar and furikake seasoning.