Preheat the oven to 425°F. Spread the onions in the bottom of the roasting pan and arrange the potatoes around the perimeter of the pan. Lay the chicken pieces on top of the onions in a single layer.
In a medium bowl, mix together the marmalade, olive oil, lemon juice, tamari, and vinegar. Pour evenly over the chicken.
Roast in the preheated oven, basting the chicken and potatoes every half hour, until the potatoes are tender and the chicken skin is golden brown, the juices run clear, and an instant-read thermometer inserted in the thickest part of a thigh and breast reads 165°F, about 1 hour to 1 hour, 15 minutes. Serve the chicken hot, with potatoes on the side.
STORAGE: Leftovers will keep, covered, in the refrigerator for 2 to 3 days.
Recipe posted with permission from Bubbe and Me in the Kitchen: A Kosher Cookbook of Beloved Recipes and Modern Twists.