In a bowl, toss diced chicken breast with a pinch of salt, white pepper, and cornstarch until evenly coated.
Heat vegetable oil in a wok or large skillet over medium-high heat. Add the chicken and stir-fry until cooked through and lightly browned, about 5-7 minutes. Remove chicken and set aside.
In the same pan, add a small drizzle of sesame oil. Stir-fry minced garlic and ginger until fragrant, about 30 seconds.
Add diced onion and green bell pepper. Cook until vegetables are crisp-tender, about 3-4 minutes.
Return chicken to the pan along with raw cashews. Stir to combine.
In a small bowl, mix soy sauce, oyster sauce, chicken broth, sugar, and a pinch of salt. Pour sauce over the chicken and vegetables.
Stir-fry everything together until the sauce thickens slightly and coats the ingredients, about 2-3 minutes.
Serve the cashew chicken in a shallow white bowl, garnished with sliced green onions.