Preheat oven to 300°.
Remove skin from turkey; cut meat from bones. Discard skin and bones; cut meat into 1 1/2-inch pieces. Sprinkle turkey with 1/2 teaspoon salt and 1/4 teaspoon pepper.
Heat oil in a small Dutch oven over medium-high heat. Add turkey; cook for 6 minutes or until browned, stirring occasionally. Remove turkey and juices from pan. Reduce heat to medium; melt butter in the pan. Add leek and carrot; cover and cook 12 minutes or until leek begins to brown, stirring occasionally.
Return turkey and juices to pan. Sprinkle flour over turkey mixture; stir well to coat. Add 1/2 teaspoon salt, 1/4 teaspoon pepper, broth, sugar, and beer. Bring to a boil; cover. Place in oven. Bake at 300° for 50 minutes or until turkey is tender. Stir in mustard and vinegar; sprinkle with parsley.