2.

Add onion and cook, stirring, until softened, about 2 minutes. Add oregano and bay leaves and cook, stirring, until aromatic, about 30 seconds. Add vinegar and stock. Return chicken to pot, bring to a boil over high heat, then reduce to a bare simmer. Cover the pot and cook, turning chicken occasionally, until chicken registers 145°F when an instant-read thermometer is inserted into the center of the thickest part, 20 to 30 minutes. Transfer chicken to a bowl and set aside. Continue cooking the sauce at a hard simmer, stirring, until reduced to about half its original volume, about 5 minutes longer.