Preheat the oven to 375 degrees F. Set the hen breast side down on a cutting board. With kitchen shears or a sharp knife, cut along both sides of the hen’s backbone and remove the bone. Place the hen breast side up and press it flat. Cut it in half down the middle of the breastbone. Place the hen halves, skin side up, in a small roasting pan or oven proof skillet. Brush skin with olive oil; season with salt and pepper. Roast for 50 minutes, basting occasionally with any pan juices, or until cooked through.
While the hen cooks, place the port, jelly, vinegar, shallot, orange juice, soy sauce, water and rosemary in a small saucepan and bring to a simmer. Stir and simmer 3 to 4 minutes, until the jelly is melted and well combined with the other ingredients. Season with black pepper, and then remove sauce mixture from the heat and reserve.
When the hen halves are cooked, set on heated plates. Pour the sauce mixture in the pot into the roasting pan, set over medium-high heat, and return to a simmer. Pour the simmering sauce over the hens and serve.
Note: Red currant jelly, also sometimes also called confiture, can be found alongside the jams and jellies sold at Thrifty Foods. If unavailable, you could try another type of jelly in this recipe, such as apple or pomegranate.
Note: Cornish game hen is most often sold frozen in our meat dept. The safest way to thaw it, is to set the hen in a sided dish in the refrigerator overnight. The next day at dinner time it should be thawed and ready to prepare.