Thinly slice chicken breasts into bite-sized pieces and coat evenly with cornstarch. Set aside for 10 minutes.

Heat vegetable oil in a large wok or skillet over medium-high heat. Add coated chicken and cook until golden brown, about 5-7 minutes. Remove from wok and keep warm.

In the same wok, add more oil if needed, then add minced ginger, minced garlic, and red pepper flakes. Sauté for 30 seconds until fragrant.

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

Add cooked chicken and sliced red bell peppers to the wok, stirring well to coat in sauce. Cook for an additional 3-4 minutes.

Stir in chopped green onions before removing from heat. Garnish with toasted sesame seeds, if desired.

Serve hot over rice and enjoy your meal!