Trim fat from meat. If necessary, cut meat to fit into a 3 1/2- or 4-quart slow cooker. Place frozen onions in cooker. Place meat on top of onions. Sprinkle meat with salt and pepper. In a small bowl combine the broth, vinegar, tomato paste, tapioca, garlic, and Italian seasoning. Pour mixture over meat.
Cover and cook on low-heat setting for 8 to 10 hours or on high-heat setting for 4 to 5 hours.
Transfer meat to a serving platter. Skim off fat from cooking liquid. Serve meat with Soft Polenta and cooking liquid. Sprinkle with parsley. If desired, garnish with cheese.
In a medium saucepan bring 2 3/4 cups water to boiling. Meanwhile, in a medium bowl stir together cornmeal, 1 cup cold water, and salt. Slowly add cornmeal mixture to boiling water, stirring constantly. Cook and stir until mixture returns to boiling; reduce heat to medium-low. Cook for 10 to 15 minutes or until mixture is very thick and tender, stirring frequently and adjusting heat as necessary to maintain a slow boil.