Place the sauce ingredients, except the mandarin oranges, in a medium-sized pot and set over medium heat. Bring to a gentle simmer and cook, stirring, until the mixture becomes fluid and the cranberries begin to just fall apart, about 15 minutes. Remove from the heat and gently stir in the oranges. Cool to room temperature, transfer to a tight-sealing container and keep in the fridge until the turkey is ready (can be made a day or two in advance). Preheat the oven to 350 degrees F. Place the turkey in parchment paper-lined roasting pan. Brush with the melted butter; season with the sage, salt and pepper. Roast the turkey for 70 to 80 minutes, or until the internal temperature of the breast reaches 170 degrees F, (77 degrees C) on a meat thermometer. Let the turkey rest for 10 minutes before thinly slicing and arranging on a platter. Serve the cranberry sauce in a bowl alongside.