Stuff the cavities of the Cornish hens with the apple and orange sections. Season with Creole seasoning and salt. Place on a roasting pan, breast side down, and put in the oven. Immediately lower the oven temperature to 350. Roast for 45 minutes, then turn up the heat to 425 for a final five minutes. The internal temperature should be about 175 on a meat thermometer shoved in the thigh.
While the birds are in the oven, make the sauce. In a saucepan over medium-low heat, cook the onions in 1 Tbs, butter, stirring often, until they become light brown uniformly.
Add the butter and flour, and make a blond roux.
Whisk in the tawny port. Bring it to a boil and hold it there, whisking often, until the liquid is reduced by half.
Add the stock and bring to a boil. Dissolve the pepper jelly into the sauce, then strain.
Return the sauce to a very light simmer, and add the grapes. Check seasonings and add salt and pepper as needed.
Place a whole roasted Cornish hen on each dinner plate, and serve the sauce around it.