In a small mixing bowl, whisk together the ingredients for the sauce. Set aside.
In a medium mixing bowl, toss the chicken with 2 tablespoons of cornstarch.
In a large skillet over medium high heat, add 1 tablespoon of oil. Once hot, add the chicken and season with salt and pepper. Cook about 5 - 6 minutes, flipping frequently to brown on all sides.
Add the chopped vegetables to the skillet. Stir and cook for 3 - 4 minutes more, until the vegetables are barely tender and the chicken is cooked through.
Pour the sauce into the skillet. Bring to a simmer over medium high heat.
In a small bowl, stir together 1 teaspoon cornstarch and 2 teaspoons of water. Pour the mixture into the skillet and simmer and additional 2 - 3 minutes, until the sauce bubbles and thickens.
Remove the pan from the heat and stir in the cashews.
Serve immediately. Optionally, serve with a side of white rice and topped with sesame seeds and green onions.