Press Sauté; cook bacon in Instant Pot until crisp. Remove to paper towel-lined plate. Drain off all but 2 tbsp drippings.
Add leek, onion and carrots to pot; cook and stir about 3 Minutes or until vegetables are softened. Stir in broth, scraping up browned bits from bottom of pot. Stir in potatoes, cabbage, salt, caraway seeds, pepper and bay leaf; mix well.
Secure lid and move pressure release valve to Sealing position. Press Pressure Cook or Manual; cook at High Pressure 4 Minutes.
When cooking is complete, use natural release for 10 Minutes, then release remaining pressure. Remove and discard bay leaf.
Whisk ½ cup hot soup into sour cream in small bowl until blended. Add sour cream mixture and bacon to soup; mix well. Garnish with parsley.