- Combine salt and pepper; season short ribs on all sides. Heat oil in large heavy 6-qt. pot on medium-high heat. Working in batches, cook short ribs 10 min. or until browned on all sides, turning often. Transfer ribs to slow-cooker; add garlic.
- Discard all but 1 tablespoon drippings from pot. Reduce heat to medium; add onions and fennel. Cook 3 - 4 min. or until onions are translucent, stirring frequently. Add broth; cook until liquid is reduced by half while gently scraping browned bits from bottom of pot. Remove from heat; stir in sauce. Pour mixture over ribs in slow-cooker; cover with lid.
- Cook on HIGH 3-4 hours (or on LOW 7-8 hours) or until ribs are tender and falling off the bones. Remove ribs from sauce; skim sauce of excess fat. Serve meat topped with sauce.
Reserve fronds from fennel bulb; chop and sprinkle over each serving.
Serve with cooked polenta to soak up the flavorful sauce.