In a mixing bowl, combine thinly sliced chicken breast with cornstarch and let it sit for 5 minutes.

Heat a wok over medium-high heat, add vegetable oil, and cook the chicken for 5-7 minutes until golden brown.

Add minced ginger, garlic, and red pepper flakes to the wok for 30 seconds until aromatic.

Whisk together soy sauce, water, brown sugar, and hoisin sauce in a bowl, then pour into the wok and simmer for 2 minutes.

Return cooked chicken and red bell pepper to the wok, tossing to coat and cooking for an additional 3-4 minutes.

Mix in chopped green onions and sprinkle with sesame seeds if desired, then remove from heat.

Serve hot over steamed rice, allowing the rice to soak up the sauce.