Combine first 4 ingredients in a shallow dish. Cover and marinate in refrigerator 2 hours, turning occasionally.
Preheat oven to 450°.
Combine potatoes and the next 4 ingredients (potatoes through pepper) in a medium bowl; toss well. Arrange potato mixture on a baking sheet coated with cooking spray. Bake at 450° for 30 minutes or until tender, stirring occasionally.
While potatoes are baking, prepare chicken. Heat 1 teaspoon oil in a large Dutch oven over medium-high heat. Add onion, and sauté 8 minutes, stirring frequently. Add wine, and bring to a boil. Stir in garlic. Place chicken, breast sides up, on top of onion. Add broth, and bring to a boil. Cover, reduce heat to medium, and cook 15 minutes or until chicken is done. Remove chicken from pan with a slotted spoon; keep warm. Bring the broth mixture to a boil, and cook until reduced to 2 cups (about 15 minutes). Combine cornstarch and water; add to pan, and bring to a boil. Cook 1 minute, stirring constantly. Pour sauce over the chicken. Serve with roasted potatoes.