Start the meal by rinsing and cooking the Jasmine rice according to package directions so it’s ready when the stir-fry finishes.
Cut the Boneless skinless chicken thigh into bite-sized pieces and season lightly with White pepper.
Prepare the produce: slice the Onion into wedges, core and thinly slice the Red bell pepper, mince the Garlic, and cut the Spring onions (scallions) into 1–2 inch lengths. Break or slice the Dried red chilies if you want their heat distributed more evenly (remove seeds to reduce heat).
Heat a large wok or heavy skillet over medium-high heat and add a tablespoon of Neutral oil. When hot, add the Cashew nuts and toast, stirring, until golden on all sides. Remove and set aside.
Return the pan to high heat and add another tablespoon of Neutral oil. Fry the Dried red chilies briefly until fragrant, then add the minced Garlic and stir for about 15–30 seconds until aromatic.
Add the chicken pieces and stir-fry over high heat until they are mostly cooked through and starting to brown, about 4–6 minutes.
Mix the sauce: stir together Oyster sauce, Light soy sauce, a splash of Fish sauce, a little Dark soy sauce for color, Palm sugar and a few tablespoons of Water to loosen. Pour this mixture over the chicken and stir to coat, letting it bubble briefly so the flavors meld and the sauce thickens slightly.
Toss in the sliced Onion and Red bell pepper and continue to stir-fry until the vegetables are tender-crisp, about 2–3 minutes. Return the toasted Cashew nuts to the wok and fold everything together.
Stir in the Spring onions (scallions), adjust seasoning to taste (add more Fish sauce or a pinch of Palm sugar if needed), and remove from heat.
Serve the Kai Med Ma Muang immediately over the hot Jasmine rice, scattering any remaining cashews on top for extra crunch.
