Cut steaks in half; rub with taco seasoning. Place in a 3-qt. slow cooker coated with cooking spray. Top with onion, chiles and vinegar. Cover and cook on low for 8-9 hours or until meat is tender. , Remove steaks and cool slightly; shred meat with 2 forks. Return to slow cooker; heat through. , Spoon about 1/2 cup meat mixture into the center of each tortilla. Top with cheese, tomato and sour cream. Fold bottom and sides of tortilla over filling and roll up.