Combine first 3 ingredients in a large zip-top plastic bag. Add the turkey; seal bag, and shake to coat.
Heat oil in a large ovenproof Dutch oven over medium-high heat. Add the turkey, and cook 5 minutes, browning well on all sides. Remove turkey from pan; set aside.
Add broth and sherry to pan, and stir to deglaze pan. Return turkey to pan; add onion and garlic, and bring to a boil. Cover and bake at 350° for 1 hour and 15 minutes or until turkey is tender. Remove from oven, and let stand for 5 minutes. Stir in the sour cream, and serve over noodles.