Add onions to bottom of slow cooker. Top with turkey thighs. In a small bowl combine remaining turkey ingredients and pour over top. Secure lid and cook for 8 hours on low or 5 hours on high.
In the last 30 minutes of cook time, remove turkey to bowl. Shred turkey and return to slow cooker. Toss to coat and secure lid to continue cooking for remainder of cook time.
In a bowl, combine cabbage, oil, vinegar and lemon juice. Toss to coat.
Preheat a griddle to medium-high. Warm up tortillas for about a 45 seconds on each side before building the wrap.
Build the wrap - lay out a tortilla and sprinkle with cheese. Using a slotted spoon, add a portion of turkey and onions. Top with cabbage. Fold ends over and roll up wrap. Cut in center on the diagonal to serve.