- Combine 2 cups Cider and Grand Marnier in saucepan. Boil until reduced by half, about 15-20 minutes.
- Blend cornstarch with remaining 1/4 cup of Cider; stir into hot mixture until thickened. Stir in orange and lemon juices.
- Place halibut in baking dish, add water to cover bottom, bake covered at 400°F for about 20 minutes until just done. Serve with sauce ladled over.