In a bowl, combine the chicken pieces with salt, pepper, and cornstarch. Toss until the chicken is evenly coated.
In a separate bowl, mix together the hoisin sauce, chili garlic sauce, chicken broth (or water), and rice vinegar.
Heat the vegetable oil in a large skillet or wok over medium-high heat. Once hot, add the marinated chicken and cook until browned and cooked through, about 5-7 minutes.
Once the chicken is fully cooked, add the chopped onion and minced garlic to the skillet. Sauté for 2-3 minutes until the onion becomes translucent and fragrant.
Pour the prepared sauce over the chicken and onion mixture. Stir well and let it simmer for another 2-3 minutes.
Finally, stir in the roasted cashews and diced green onions. Cook for an additional minute, just until everything is heated through.
Serve your Easy Cashew Chicken over a bed of fluffy cooked white rice.