In a mixing bowl, combine tomato sauce, vinegar, garlic, chili powder, cumin, oregano, sugar, salt and pepper. Set aside.
Add 2 tablespoons olive oil to a large skillet over medium heat. Once the oil is hot add chicken breasts to the pan.
Cook chicken for 5 minutes on the first side.
Flip chicken and cook for another 5 minutes on the second side.
Add the tomato sauce mixture to the skillet.
Increase heat and bring the sauce to a boil.
Once sauce comes to a boil, cover pan with a lid and reduce heat to low. Simmer, covered for about 20 minutes and chicken is cooked through.
Using tongs remove chicken from the pan and place on a cutting board.
Cut chicken into small pieces and return to the pan. Continue to cook until everything is heated through.