In medium bowl, mix together tomato sauce, vinegar, garlic, chili powder, cumin, oregano, and sugar. Season with adobo; set aside.
Heat oil in large skillet over medium-high heat. Season chicken with adobo. Cook chicken, turning once, until light golden brown on both sides, about 5 minutes. Add reserved tomato sauce mixture to pan; bring to a boil (be careful, the tomato sauce can splatter). Lower heat to medium low. Simmer, covered, until cooked through (thermometer will register 170°F when inserted into thickest part of breast), flipping once, about 20 minutes.
Transfer chicken to cutting board; reserve sauce in pan. Remove and discard bones and skin. Using two forks, shred chicken breast. Transfer chicken to skillet with sauce, mixing to combine; continue to cook until sauce reduces and blends into chicken, and mixture begins to caramelize, about 10 minutes more.
Transfer chicken mixture to serving bowl. Spoon into warmed corn tortillas. Garnish with lettuce, tomatoes, avocados and/or onions, if desired. Sprinkle with hot sauce, if desired.