HEAT the sesame oil in a large skillet (or wok) over medium-high heat. Add the chicken and brown for 3-4 minutes.
ADD the bell pepper, broccoli, water chestnuts, and cashews and sauté for 8-10 minutes, until the veggies begin to soften.
WHILE the chicken and veggies are cooking, whisk together the soy sauce, rice vinegar, tomato paste, chicken stock, ginger, garlic powder, crushed red pepper, Swerve, and xanthan gum.
POUR the sauce over the chicken and veggies, reduce heat to medium-low, and simmer for 10 minutes.
DIVIDE into 3 portions. Garnish with green onion and sesame seeds.