Place potato in a large saucepan, and cover with water; bring to a boil. Reduce heat, and simmer 15 minutes or until tender. Drain and plunge potato into ice water; drain. Place potato in a large bowl.
Combine egg whites, mayonnaise, parsley, green onions, and salt. Add curry paste and water to mayonnaise mixture; stir well. Pour over cooled potato; toss gently to coat. Cover and chill 8 hours.