Mix together egg, salt, ground black pepper, and 2 tablespoons of cornstarch in a bowl. Add the chicken to marinate. Let it sit for 5 minutes.
Heat 2 tablespoons of olive oil in a nonstick skillet over medium-high heat to sauté the marinated chicken. Stir frequently for 10 minutes until they're browned on all sides.
After the chicken is cooked, transfer it to a large bowl and set aside.
In the same skillet, make the sauce mixture: Turn on medium heat, add garlic, ginger, and 1 tablespoon of olive oil. Stir.
Continue to add the following ingredients to the skillet successively: 1 tablespoon of cornstarch, soy sauce, honey, and chicken broth (it’s important that it is done in this order, otherwise the sauce will be muddy). Let it simmer and stir frequently until it starts to bubble and thicken.
Add apple cider vinegar and transfer the cooked chicken back into the sauce mixture. Stir around to coat the chicken chunks evenly.
Sprinkle in red pepper flakes, chopped scallions, and roasted sesame seeds. Finally, add sesame oil and give it one last stir.
Remove the skillet from heat.
Serve sesame chicken over a bed of hot cooked rice and steamed broccoli, sprinkle a few pinches of roasted sesame seeds and chopped scallions on top. Enjoy!