- For veal roast:
- 1 (4.5 pound) tied boneless loin of veal roast
- 1 teaspoon salt
- 1/2 teaspoon black pepper
- 1 tablespoon vegetable oil
- 2 tablespoons unsalted butter
- 1 medium onion, finely chopped
- 1 celery rib, finely chopped
- 1 large carrot, finely chopped
- 6 sprigs fresh flat-leaf parsley
- 6 sprigs fresh thyme
- 1 Turkish bay leaf
- 1 cup dry white wine
- For soubise:
- 1/3 cup long-grain white rice
- 2 tablespoons unsalted butter
- 1 pound onions, halved lengthwise and thinly sliced crosswise
- 1/2 teaspoon salt
- 1/3 cup chicken broth or water
- For duxelles:
- 1 pound mushrooms, minced
- 3 tablespoons unsalted butter
- 1/2 ounce black truffles, finely chopped (optional)
- 1/4 cup heavy cream
- 1/4 teaspoon salt, or to taste
- 1/8 teaspoon black pepper
- For Mornay sauce:
- 1 1/2 cups whole milk
- 4 1/2 tablespoons unsalted butter
- 6 tablespoons all-purpose flour
- 1/3 cup coarsely grated Gruyere
- 1/2 teaspoon salt
- 1/8 teaspoon black pepper
- 1/8 teaspoon freshly grated nutmeg
- Braise veal: Position oven racks in upper and lower thirds of oven and preheat to 325 degrees F.
- Pat veal dry and sprinkle with salt and pepper. Heat oil and 1 tablespoon butter in 5- to 6-quart pot over moderately high heat until foam subsides, then brown veal on all sides, turning with tongs, about 10 minutes. Transfer veal to a plate and discard fat from pot.
- Melt remaining tablespoon butter in pot and cook onion, celery, and carrot over moderate heat, stirring and scraping up any brown bits, until softened, about 5 minutes.
- Wrap parsley, fresh thyme (if using), and bay leaf in a square of cheesecloth and tie into a bundle with string to make a bouquet garni, then add to vegetables along with wine and dried thyme (if using). Put veal on top and bring to a simmer.
- Cover pot with lid, then transfer to lower third of oven and braise veal until thermometer inserted 2 inches into center of meat registers 145 degrees F, about 1 1/2 hours.
- Transfer veal to a cutting board and let stand 30 minutes (internal temperature will rise to 155 degrees F). Pour cooking juices from pot through a fine-mesh sieve into a 4-cup measure, pressing on and discarding solids. Skim off fat and reserve juices, adding any juices that have accumulated on plate from veal, for Mornay sauce.
- Make soubise while veal braises: Parcook rice in a large saucepan of boiling salted water 5 minutes, then drain in a sieve and rinse.
- Heat butter in a 10-inch ovenproof skillet over moderately low heat until foam subsides, then stir in onions and salt. Cover tightly with a lid or a double layer of foil and cook onions over low heat, stirring occasionally, 5 minutes. Stir in rice and broth and bring to a simmer.
- Cover skillet tightly, then transfer to upper third of oven and bake until rice and onions are very soft, about 1 hour. (Leave oven on.)
- Transfer soubise to a food processor and pulse until coarsely pureed. Transfer to a bowl to cool.
- Make duxelles while veal and soubise cook: Put a handful of mushrooms in a clean kitchen towel (not terry cloth), then gather towel around mushrooms and wring them over sink to squeeze out as much liquid as possible. Wring out remaining mushrooms, a handful at a time, in same manner.
- Heat butter in a 12-inch heavy skillet over moderately high heat until foam subsides, then saute mushrooms and truffles (if using), stirring, until lightly browned and any liquid mushrooms give off is evaporated, 6 to 8 minutes. Stir in cream, salt, and pepper and cook, stirring, until cream is absorbed by mushrooms, about 1 minute. Transfer to a bowl and cool.
- Make Mornay sauce while veal stands: Add enough milk to reserved veal juices to total 3 cups. Melt butter in a 2-quart heavy saucepan over moderately low heat, then add flour and cook over low heat, whisking constantly, 3 minutes. Add milk mixture in a stream, whisking, and bring to a boil, whisking. Reduce heat to low and gently simmer, whisking occasionally, 10 minutes. Remove from heat and add Gruyere, whisking until melted, then whisk in salt, pepper, and nutmeg.
- Assemble veal Orloff: Move top rack to middle of oven and increase temperature to 375 degrees F.
- Stir 1/4 cup soubise into duxelles, then transfer remaining soubise to a sealable plastic bag. Transfer duxelles mixture to other sealable plastic bag, then seal each bag, squeezing out excess air. Snip off 3/4 inch from a bottom corner of each bag.
- Remove string from veal, then trim off fat layer and ends of veal and discard. Cut roast crosswise into 16 slices (1/4 inch thick), keeping slices together. Transfer 1 slice of veal to end of ovenproof platter, then pipe about 1 1/2 tablespoons soubise onto half of slice, starting at bottom of slice and working toward top. Pipe about 1 1/2 tablespoons duxelles on other half of slice in same manner. Overlap with another slice of veal, leaving about 1/2 inch of stuffing exposed. Repeat with remaining veal slices and remaining soubise and duxelles, keeping slices aligned.
- If necessary, heat Mornay sauce over low heat, stirring, until loose enough to spoon, then spoon 1/2 to 3/4 cup over top and sides of veal, covering slices and stuffings thinly but completely.
- Bake veal Orloff, uncovered, until heated through and Mornay sauce glazes veal, 15 to 30 minutes.
- Heat remaining Mornay sauce over moderate heat, stirring occasionally (thin with a little milk, if necessary), until hot and transfer to a gravy boat to serve on the side.