In a large skillet heat oil over medium-high heat. Cook meat, half at a time, in hot oil until brown. Drain off fat. Place meat to a 3-1/2- or 4-quart slow cooker. Add onions and carrots. Sprinkle with garlic, thyme, salt, and pepper. Pour tomatoes and broth over mixture in cooker.
Cover and cook on low-heat setting for 7 to 9 hours or on high-heat setting for 3-1/2 to 4-1/2 hours.
If using low-heat setting, turn cooker to high-heat setting. Stir in zucchini and green beans. Cover and cook for 30 minutes more. If desired, serve over hot cooked couscous. Top each serving with Gremolata.
In a small bowl combine parsley, lemon peel, and garlic.