Through the feed opening of a running blender add, 1 at a time, vinegar, soy sauce, scallions, black pepper, and salt. Then leaving the blender running, add the olive oil in a slow thin stream.
Toss together the hearts of palm, onion, bell pepper, and mango. Stir in enough of the dressing to coat, and serve any additional dressing on the side.
2007, Robert Irvine, All Rights Reserved