Place a large skillet over medium high heat and add canola oil. Add mushrooms and allow them to cook, undisturbed for four minutes. Stir and continue to cook for another four minutes. The mushrooms should have begun to caramelize.
Add in the onions and green beans and turn the heat down to medium. Cook for another five minutes, stirring occasionally.
Turn the heat down to low and add the garlic and ginger and cook for two minutes.
In a separate bowl, whisk together the brown sugar, soya sauce, rice wine vinegar, hot sauce,water and cornstarch until sugar is dissolved.
Stir the sauce into the mushroom mixture and immediately remove from the heat. Stir in cashews, basil and sesame oil.