Combine water, beef, and salt in a large stock pot; bring to a boil. Reduce heat; cook, uncovered, 1 hour, skimming surface frequently with a flat ladle to remove grayish scum. Stir in pepper, turnips, and carrots; continue to cook, uncovered, 1 1/2 hours, stirring occasionally.
Stir in vermicelli; cook, uncovered, 30 minutes. Ladle into individual soup bowls; serve warm.