Place the sugar in a heavy 4-quart saucepan and cook over high heat until a rich caramel color, 3 to 4 minutes, stirring almost constantly with a wooden spoon; be careful not to let it burn. Add the rhubarb, stirring until pieces are well coated, then promptly add the consommé (not fond de veau), carrots, celery, leeks, onions, turnips, and shallots; cook until mixture reduces to about 1 cup, about 20 minutes, stirring occasionally. Remove from heat and strain through chinois, using the bottom of a sturdy ladle to force as much through as possible. Return to saucepan and cook over medium heat until reduced to 1/2 cup, about 15 minutes, and set aside. (This may be done up to two days ahead; keep refrigerated.)
Heat oven to 350°. With a sharp thin-bladed knife, carefully trim away any green spots on the foie gras caused by contact with the gall bladder. Season both sides of the foie gras very generously with salt and pepper; set aside.
In a medium sized bowl, combine all the ingredients for this braising bed. Place the oil in a heavy 13 × 9-inch roasting pan and heat over high heat on top of the stove about 1 minute. Add the braising-bed mixture and sauté until it starts to brown, about 10 minutes, stirring frequently. Add the consommé and continue cooking and stirring about 3 minutes more, then mound the vegetables in the center of the pan and place the foie gras on top. Remove from heat and seal pan with aluminum foil, pierce foil 2 or 3 times with the tip of a pointed knife so steam can escape during cooking. Bake in the preheated oven for 8 minutes; then momentarily remove pan from the oven, uncover, and turn foie gras over with two sturdy rubber spatulas to prevent marring the foie gras’s smooth surface, being very careful to keep it intact. Cover the pan and continue baking until done, about 10 minutes more; do not overcook, or the foie gras will lose its unique buttery texture. (To test doneness, pierce foie gras with a thin wood or metal skewer; then press very gently around skewer hole. If juices run slightly pink, not clear and not bloody, it’s done.) Transfer foie gras to a plate and cover loosely with foil to keep warm while finishing the sauce.
To finish the sauce, place the roasting pan with the braising liquid and vegetables in it over high heat on top of the stove and bring to a boil. Add the port and return to a boil; then continue boiling until liquid reduced to about 2/3 cup, about 8 minutes more, stirring occasionally. Strain braising liquid through the chinois into a bowl, using the bottom of a sturdy ladle to force as much through as possible. Skim all fat from surface and add remaining liquid to the reserved rhubarb sauce. Reheat sauce and, if needed, let it reduce to a thin sauce consistency. Season to taste with salt and pepper and serve immediately
Cut the foie gras crosswise into 1-inch-thick slices on the diagonal. Spoon 2 to 3 tablespoons sauce on each heated serving plate and arrange a slice of foie gras on top of sauce.
* Fond de veau is made from a reduction of the feet of veal, tomato paste, vegetables, and water. It is thick in consistency, compared with the consommé. The fond de veau is used to finish the sauce.
© 1996 All rights reserved. Published by Wiley.