Preheat oven to 425°F (220°C). Pat the duck completely dry with paper towels. This is KEY for crispy skin!
Combine salt and pepper in a small bowl. Generously rub the mixture all over the duck, inside and out.
In a medium saucepan, whisk together orange zest, orange juice, honey, orange marmalade, soy sauce (or tamari), rice vinegar, grated ginger, and minced garlic.
Bring the glaze to a simmer over medium heat, then reduce the heat and let it simmer for 10-15 minutes, or until slightly thickened.
Place the duck on a roasting rack inside a roasting pan. If using, scatter aromatic vegetables (onion, carrots, celery) in the bottom of the pan.
Roast the duck for 30 minutes at 425°F (220°C).
Reduce the oven temperature to 325°F (160°C) and continue roasting for another 1 ½ - 2 hours, or until a meat thermometer inserted into the thickest part of the thigh registers 165°F (74°C). Baste the duck with the orange glaze every 20-30 minutes during the roasting process.
Remove the duck from the oven and let it rest for at least 15 minutes before carving.
Carve the Roast Duck with Orange Glaze and serve immediately. Drizzle with pan juices.