How to Make It
Cook mushrooms in 1 tablespoon hot oil in a large skillet over medium-high 8 minutes or until mushrooms are browned. Season with 1/4 teaspoon salt and 1/4 teaspoon pepper, and place in a 5- or 6- quart slow cooker.
Add 1 tablespoon oil to skillet; add onions, celery, carrots, and garlic. Sauté 6 minutes or until lightly browned; add to slow cooker. Stir wine and tomatoes into mixture in slow cooker.
Season turkey evenly with oregano, remaining 1/2 teaspoon salt, and remaining 1/2 teaspoon pepper. Add remaining 1 tablespoon oil to skillet; cook turkey in hot oil over medium-high 6 minutes, turning to brown on all sides. Place turkey in slow cooker; nestle into tomato mixture so that turkey is partially covered.
Cover and cook on LOW 5 hours or until turkey is very tender. Remove turkey from slow cooker; cool slightly. Turn slow cooker to HIGH. Whisk together cornstarch and 2 tablespoons water; whisk into mixture in slow cooker. Cook, uncovered, on HIGH 15 minutes or until sauce is thickened, stirring occasionally.
While sauce thickens, remove meat from drumsticks and shred gently. Stir turkey into sauce in slow cooker.
Combine parsley, lemon zest, and sea salt. Serve ragout over polenta; sprinkle with parsley mixture.