I recently acquired a copy of Martha Stewart’s Hor D’Oeuvres Handbook and became taken with her flair for small bites with beautiful presentation. The onion relish here was inspired by Dancer’s Chicken with Balsamic Onions. You can prepare the onions a day or so ahead of time and finish the tarts just before serving. I tend to offer a lot of variety so I keep the batches of each hors d’oeuvre small, but this can be easily doubled. Don't let the preparation time scare you, its mostly simmering time that frees you to attend to other things. These tarts are just wonderful served along with a zesty red wine.