Prepare bok choy by washing and drying leaves and stems. Tear leafy part from stems, slice the stem pieces and chop the leafy part.
Heat the oil in a wok or skillet over high heat. Add garlic and onions, stir-fry for 3 minutes. Add carrots and stir-fry 3 minutes. Add green beans and bok choy stems and stir-fry 3 minutes. Add leaves and stir-fry 1 minute. Add broth and red pepper flakes and simmer up to 2 minutes. Add soy sauce and serve.