MARINATE CHICKEN: Whisk the egg, 1 TBS soy sauce and marinade spices together in a large bowl or freezer bag. Add the sliced chicken and turn to coat. Marinate while you prep the rest of the ingredients, preferable 30 minutes. You can also refrigerate overnight, then let the chicken sit at room temperature for 30 minutes before breading.
MAKE SAUCE: Whisk the Sauce ingredients together in a medium bowl until the cornstarch is completely dissolved; set aside. BREAD CHICKEN: In a separate large freezer bag, combine the flour, cornstarch and chili powder. Remove the chicken from the marinade, dab off excess with paper towels, then add to the breading bag. (To quickly remove excess marinade, I plop the chicken on a wad of paper towels using a slotted spoon.) Shake the chicken until well coated, pressing coating into chicken. If needed, open the bag and use your hand to separate and coat any last pieces.
COOK: Heat 1/4 cup canola, vegetable or peanut oil over medium-high heat in a large NONSTICK skillet (you may use less oil but it will be less crispy). Working in 2-3 batches, shake off excess breading from chicken and add to the sizzling oil in a single layer. Cook for about 4 minutes, or until cooked through, flipping halfway. Remove chicken to a paper towel lined plate. Add another drizzle of oil to the skillet if needed and repeat with remaining chicken. Set aside. CASHEWS: Toast the cashews in a dry, large cast iron skillet over medium heat until toasted in spots, stirring a few times; remove cashews from the skillet. STIR FRY: Heat a drizzle of oil over medium-high heat in the now empty skillet. Once hot, add the onion and bell pepper and stir fry for 2 minutes. Add the ginger and garlic and stir fry for 30 seconds.. ADD SAUCE. Whisk the sauce again to recombine. Add to the skillet and bring to a simmer, stirring often until thickened, about 1 minute.
COMBINE: Add the chicken and cashews and stir to coat. Garnish with sesame seeds and green onions. Serve immediately. The sooner you enjoy the chicken, the crispier it will be. If everyone isn't seated at the table yet, wait to add the chicken until ready to serve.