Trim fat from meat; rub seasoning mix over both sides of meat. Place meat in an electric slow cooker coated with cooking spray; add onion, vinegar and green chiles. Cover with lid; cook on low-heat setting for 9 hrs. Remove meat from slow cooker, reserving cooking liquid; shred meat with 2 forks. Combine meat and reserved cooking liquid; stir well.
Warm beans and tortillas according to package directions. Spread 2 tbsp beans down middle of each tortilla. Spoon a heaping 1/3 cup meat mixture on top of beans. Top each with 2 tbsp cheese, 2 tbsp tomato, and 1 tbsp sour cream; roll up.