Season the chicken thigh pieces with salt and pepper. In a medium bowl, whisk the egg with the cornstarch until completely combined - this may take a minute or two to get it all to come together. Add the chicken thighs and stir until all of the thighs are completely coated.
In a large skillet, heat 1 TBS of the sesame oil on medium heat. Add the chicken thighs, leaving a bit of room in between each one, working in batches if necessary. They will stick together and steam instead of fry if too close. Cook on both sides until done, being gentle when flipping the pieces because you don't want to knock the breading off.
While the chicken is cooking, prepare the sauce. In a bowl, mix together the remaining 1 TBS of sesame oil, soy sauce, Swerve, apple cider vinegar, ginger, sesame seeds, and xanthan gum.
Add the sauce to the cooked chicken in the skillet and stir the pieces around to coat with the sauce. Allow to cook on low heat until sauce is warmed and has thickened slightly.