Place a large skillet over high heat with 2 turns of the pan of oil, about 2 tablespoons. Season the chicken with salt and pepper. When the pan is very hot, add in the meat and stir-fry until golden brown, about 4-5 minutes. Remove the meat from the pan and reserve on a plate.
Add another tablespoon of oil, then add the bell pepper, onion, garlic and ginger to the skillet and stir-fry until tender-crisp, 3 minutes. In a small bowl, stir together the hot sauce, tamari, Hoisin sauce, orange marmalade and stock.
Return the chicken to the skillet and pour the sauce into pan. Add the cashews to the skillet, toss to coat and continue cooking until the sauce thickens up, about 1 minute more.
Serve the stir-fry over brown rice, garnish with scallions.