Prepare sauce: Mix soy sauce honey and vinegar in a small bowl. Set aside.
In a large bowl, whisk egg whites and cornstarch together.
Add chicken to the bowl, season with salt and pepper and toss until coated.
Heat 1 tablespoon oil in a nonstick skillet on medium/high.
Add half of the chicken and cook 6-8 minutes or until golden and cooked through.
Remove to a plate and repeat the process with the remaining oil and the other half of the chicken.
Move all the chicken back to the skillet, add in garlic, onion, spinach and clementines.
Continue cooking and stirring until spinach is wilted.
Stir in sauce and heat through.
Sprinkle sesame seeds on top before serving.