In the same skillet over medium heat, brown the onions and garlic. Add oil if necessary. Dust with flour and cook for 1 more minute. Add the wine and bring to a boil while stirring. Transfer the mixture to the slow cooker and add the broth, tomatoes and thyme. Cover and cook until the meat is fork tender, about 6 hours with the cooker set to high or 8 hours with the cooker set to low. Remove the thyme. Adjust the seasoning.
