Combine cabbage, onion, and parsley.
Stir together vinegar, sugar, salad oil, and salt till sugar is dissolved.
Pour vinegar mixture over vegetables; toss to coat vegetables.
Cover and chill.
Separate yolk from white of one hard-cooked egg.
Cut up white; toss with cabbage.
Slice remaining egg; arrange atop salad.
Sieve yolk over the egg si ices.