In a medium bowl, marinate the chicken in the salt and cornstarch and set aside.
In a small bowl, mix all the ingredients listed for the sauce and set aside.
Heat 2 tablespoons of oil in a wok or large, nonstick skillet over high heat. Add the chicken in an even layer and allow it to cook, undisturbed, for 2 minutes. Flip over and allow the other side to cook for another minute. Then stir-fry until the chicken is cooked through (~4-5 minutes). Remove the chicken and set aside.
Lower the heat to medium and add the remaining tablespoon of oil. Add the garlic and ginger and sauté for 15-20 seconds. Add the onion and bell pepper and raise the heat back to high. Stir-fry until you can smell the peppery aroma of the green peppers and onions turn translucent (~4-5 min). Add the chicken back in, followed by the prepared sauce.
Stir-fry until the sauce has reduced and the chicken is fully cooked (~1-2 min). Taste and adjust salt and spice, if desired.
Add in the cashews and mix well. Garnish with toasted sesame seeds, if desired. Serve immediately with rice.