In a large saucepan bring water and salt to boiling. Add noodles and onion. Reduce heat slightly and boil gently, uncovered, for 5 minutes.
Add cabbage to boiling water and cook for 3 to 5 minutes more or till noodles and cabbage are tender. Drain well. Return noodles and cabbage to saucepan.
Stir in yogurt, caraway seed, and pepper. Heat through, but do not boil.