Preheat a wok over high heat for about 1 minute, then swirl in the oil until you see wisps of white smoke.
Add the chicken and let sit, untouched, 1 to 2 minutes, then flip and sear the other side.
Add the onion and cook 1 to 2 minutes, until it softens at the edges but stays crisp.
Add the dried chiles, Thai chiles and cashews and stir-fry 30 seconds, until they darken slightly and the oil smells toasty-spicy.
Add the red and green bell peppers and cook 1 to 2 minutes.
Add the garlic and cook about 30 seconds, until light brown and fragrant.
Pour in the nam prik pao (chili paste), Thai oyster sauce, fish sauce and MSG; stir-fry about 1 minute, until the sauce reduces to a glaze and coats the chicken and vegetables with a glossy sheen.
Finish with a sprinkle of white pepper.
Serve immediately over hot jasmine rice.
