Add stock, tomatoes and chipotle chiles and bring to a boil. Add browned chicken and reduce heat to low. Simmer, turning the chicken occasionally, until chicken registers 150 degrees on an instant-read thermometer, about 25 to 35 minutes. Transfer chicken to a cutting board and let rest until cool enough to handle. Remove skin and bones and thoroughly shred chicken meat (there should be no big chunks).
While chicken is cooling, continue cooking the sauce over medium heat, stirring frequently, until thickened and reduced by about half, about 15 to 20 minutes. Add the shredded chicken and vinegar, and bring to a bare simmer, over very low heat, for another 15 to 20 minutes, stirring, or sauce coats the shredded chicken. Use for tacos, burritos, tortas, etc.
To freeze the chicken: Cool it to room temperature. Transfer to 2-cup or 1-quart sized freezer containers; freeze up to 2 months. Place frozen chicken tinga container/s in large bowl filled with hot water about 5 minutes or until filling can be slid out of container into a saucepan. Cover and cook over low heat, stirring occasionally, until hot.
Nutrition information per ½ cup:
Sodium245 mgSaturated fat1 g