Sautee the onions in 1 tbs canola oil till browned. Add the garlic and continue to sautee for another 60 seconds. Add to slow cooker. Add all incredients except for the sour cream, lime and cheese to the slow cooker. The chicken should be in whole pieces. Cook on high for 4 hours or low for 6-8 hours. Shred the chicken in the slow cooker before serving. Top with cheese, freshly squeeze lime juice and sour cream just before serving.