Cook potato in a large saucepan of boiling, salted water for 10 minutes or until tender. Drain. Cool for 15 minutes.
Combine potato, onion, parsley and gherkin in a large bowl. Combine mayonnaise, sour cream, 1 tablespoon hot water and vinegar in a jug. Add mayonnaise mixture to potato mixture. Toss to combine. Serve
Recipe courtesy of www.taste.com.au
Serving size 4