Cut the chicken breasts into bite-sized pieces. Set aside.
Crack the egg into a bowl and with a fork beat until the egg white and yolk are well combined.
In a second bowl, combine the coconut flour, salt, and pepper. Mix well.
Add the chicken pieces into egg mixture until covered. Then dip each chicken piece in the coconut flour, covering it on all sides.
Heat a wok or large frying pan with coconut oil. When hot, add the chicken. Make sure the pieces don’t touch. If all the chicken does not fit at once, fry it in batches. Fry until golden and no longer pink inside. (It will take about 5 minutes, depending on the size of your chicken pieces.) Remove from the pan when done and let drain on a paper towel.
Add all the ingredients for the sauce to the wok or frying pan, whisk until combined, and let it simmer for a couple of minutes until the sauce has thickened.
Add the bell pepper and scallions. Cook for a couple of minutes until tender, then bring back the chicken to the wok. Toss around until everything is covered in the sauce. Garnish with sesame seeds when serving.