Prepare the Sauce: Combine the oyster sauce, dark soy sauce, fish sauce, white sugar, and water in a small bowl. Stir until evenly mixed, then set aside. Toast the Cashews: Heat the oil in a wok or large skillet over medium heat. Add the raw cashews and cook for about 5 minutes, stirring as needed, until they are dark golden and crunchy. Remove the cashews with a slotted spoon and set them aside. Cook the Aromatics: Increase the heat to high. Add the minced garlic and thinly wedged onion to the wok. Stir-fry for 30 seconds, keeping the ingredients moving so they cook quickly without overbrowning. Add the Chicken: Add the thinly sliced chicken thighs and stir-fry for 1 minute, until the outside of the chicken changes from pink to white.
Add Chilli and White Green Onion: Add the white portions of the green onions along with the sliced red cayenne pepper. Continue cooking for 1 minute, stirring frequently, until the chicken is just cooked through. Reduce the Sauce: Pour the prepared sauce into the wok. Cook for 1 minute, tossing the chicken through the sauce, until the liquid reduces to a syrup-like consistency and coats the chicken.
Finish the Stir Fry: Add the green portions of the green onions and the toasted cashews. Toss everything together for about 30 seconds, distributing the cashews and green onions throughout the chicken. Serve: Transfer the finished stir fry to a serving dish. Serve immediately with jasmine rice or another rice of your choice, and garnish with additional finely sliced red chilli if desired.
