Add ¼ cup vinegar to help loosen things up a bit. Scrape up any brown bits from the bottom of the pan with a wooden spoon and stir chicken constantly. Once liquid has evaporated, add the additional 2 Tbsp of vinegar and continuously toss again. By now, the chicken should be fully cooked and you should have released all the browned bits from the bottom of the pan. Turn down heat to a simmer to keep things warm.