Peel the turnips and place in water to cover. Add salt, bring to a boil, lower flame, and cook 20 to 25 minutes until turnips test done with a fork. Remove turnips from the water and dry on paper towels, then cut in small cubes. Toss turnips with broth while still warm.
Combine mayonnaise, sour cream, mustard, and celery seed.
When the turnips have stood in the broth 10 minutes, add sour cream, mayonnaise, and toss lightly. Dice the hard-boiled egg and add along with the onion, celery, green pepper, and parsley. Lightly toss again. Add salt and pepper to taste. Chill briefly and serve.