In a wok or large saute pan, add the grapeseed oil and when almost smoking, add the onions and bell peppers. Saute, stirring constantly, for 2 minutes. Add the green beans and mushrooms and cook for 2 minutes more.
Add the bok choy, garlic, soy sauce, and fish sauce and saute until just wilted. Add pepper, to taste, and serve immediately.
Recipe courtesy of Guy Fieri