Spray 5- to 6-quart slow cooker with cooking spray.
In slow cooker, mix sweet potatoes, onions, garlic, chili powder, cumin, tomatoes, refried beans, black beans and broth.
Cover; cook on Low heat setting 7 to 8 hours (or on High heat setting 3½ to 4 hours).
Just before serving, stir in vinegar.
Serve chili with cheese and sour cream.
Notes / Tips / Wine Advice:
Time-saver:Make quick work of chopping the garlic and onions by enlisting the help of your food processor. Start by chopping the garlic first, then add the onions and continue chopping. Depending on the size of your food processor, you may need to do the onions in batches. Either way, you save time and tears!