Mix together the soy sauce, sriracha, honey, sherry, ginger, garlic, cornstarch and pineapple juice in a bowl to make the sauce.
Place the chicken breasts into a bowl then pour half the sauce over the chicken, cover and refrigerate for 2 hours and up to 24 hours.
Pour the remaining half of the sauce into a separate container then cover and refrigerate until ready to use.
Take the chicken out of the fridge. Pat the chicken breasts with a paper towel to remove excess marinade then brush the chicken with the sesame oil.
Heat a large skillet over medium heat.
When the skillet is hot cook the chicken 5 to 7 minutes on each side or until chicken is cooked through.
Transfer the chicken to a cutting board and allow to rest for about 10 minutes. Meanwhile take the other half of the sauce out of the fridge and heat it up in the skillet over medium-low heat until thickened, about 3 minutes.