Wash ham hock, and place in an 8-quart Dutch oven; add water, and bring to a boil. Reduce heat, and simmer 1 hour or until meat is tender.
Peel turnip roots, and cut in half. Add turnip greens, turnip roots, and 1 teaspoon salt to Dutch oven; bring to a boil. Cover; reduce heat and simmer 2 hours or until greens and roots are tender.
Combine cornmeal and 1/2 teaspoon salt; mix well. Stir in boiling water. Add egg, and mix well. Drop cornmeal mixture by tablespoonfuls onto a well floured board, and roll in flour. Place dumplings over hot turnip greens; cover and cook over medium heat 15 minutes. Serve immediately with turnip greens and pot likker.