In a bowl add ¼ cup cornstarch and season with a little salt and pepper. Stir to combine with a fork. Add chicken pieces and toss to coat well.
In a large pan over medium-high heat, add vegetable oil. Drop chicken pieces and cook until both sides are golden brown. Cook chicken in one layer, do not overcrowd. If needed cook in batches. Remove chicken from the pan and set aside.
Make the Hunan Sauce:
In the meantime, add all the ingredients for the sauce into a bowl and whisk until well combined.
Cook the Vegetables:
Add a bit more vegetable oil to the pan and add vegetables. Cook for 7-8 minutes, stirring from time to time.
Add the meat and sauce:
Return the chicken to the pan and also add the sauce. Stir and coat everything into the sauce and cook for 1-2 more minutes, until the sauce thickens.
Transfer to a plate or bowl and serve Hunan chicken with a side of white rice or noodles.
Garnish with green onions and sesame seeds before serving.