This roast owes its crackly, burnished skin to a glaze of pomegranate molasses, which also infuses the gravy it's served with. Serve this with our Pistachio-Pomegranate Pilaf.
Pat goose dry inside and out. Prick skin all over with a toothpick.
Toast coriander, cumin, and sesame seeds with 1 tablespoon salt in a skillet over medium heat for 5 minutes. Let cool. Finely grind. Rub 1 tablespoon mixture inside cavity of goose, and rub the remainder over skin. Place ginger, garlic, scallions, and orange in cavity. Secure wings to body with metal skewers. Tie legs together with twine.
Place goose, breast down, on a rack set in a roasting pan. Add enough water to come just below rack. Cover with parchment and several layers of foil. Bring to a simmer over 2 burners, and steam goose 1 hour, adding water as necessary. Flip goose, and steam 1 1/2 hours more.
Transfer goose to a wire rack; let cool for 10 minutes. Carefully tip goose over a bowl to catch juices from cavity. Let cool. (Goose and juices can be refrigerated overnight; let stand at room temperature for up to 1 hour before roasting.)
Preheat oven to 450 degrees. Place vegetables on a rimmed baking sheet. Add water and reserved juices from cavity, and roast vegetables for 30 minutes.
Place goose on wire rack over vegetables, and brush goose with 3 tablespoons molasses. Roast, adding water if vegetables darken too quickly, until goose is browned, about 15 minutes.
Transfer goose and rack to a second rimmed baking sheet, and let rest. Discard vegetables. Place baking sheet with pan juices over 2 burners on medium heat. Stir in sherry, and bring to a boil. Strain into a large saucepan. Stir in pomegranate juice, stock, remaining molasses, salt, and pepper. Boil until reduced to 1 1/2 cups, 10 to 12 minutes.
Transfer goose to a platter. Garnish with pomegranates. Serve with gravy.