When planning the Delmonico reopening, we wanted to bring back the tableside service that was so popular in dining rooms long ago. Steak Diane is one of those dishes we were proud to include in this tableside repertoire. Supposedly named for the Roman goddess of the hunt, Diana (or Diane) style was originally a way of serving venison. Through the years, though, the preparation has come to mean sauteing thinly sliced or pounded filet mignon in butter and then flambeing and basting it in a rich Cognac sauce. Steak Diane takes me back to my Commander's Palace days, when this was a favorite lunch dish of proprietor Dick Brennan. Once we put it on the menu at Delmonico, it quickly became a favorite of a new generation of New Orleanians, including one of our regular diners, Glenn Vesch. These filets are cooked to medium-rare. If you want your meat more done, slightly increase the initial cooking times.
Season the beef medallions on both sides with the salt and pepper.
Melt the butter in a large skillet over medium-high heat. Add the meat and cook for 45 seconds on the first side. Turn and cook for 30 seconds on the second side. Add the shallots and garlic to the side of the pan and cook, stirring, for 20 seconds. Add the mushrooms and cook, stirring, until soft, 2 minutes. Place the meat on a plate and cover to keep warm.
Tilt the pan towards you and add the brandy. Tip the pan away from yourself and ignite the brandy with a match. (Alternatively, remove the pan from the heat to ignite, and then return to the heat.) When the flame has burned out, add the mustard and cream, mix thoroughly and cook, stirring, for 1 minute. Add the veal stock and simmer for 1 minute. Add the Worcestershire and hot sauce and stir to combine. Return the meat and any accumulated juices to the pan and turn the meat to coat with the sauce.
Remove from the heat and stir in the green onions and parsley. Divide the medallions and sauce between 2 large plates and serve immediately.
Reduced Veal Stock:
Preheat the oven to 375 degrees F.
Place the bones in a large roasting pan and toss with the oil. Roast, turning occasionally, until golden brown, about 1 hour.
Remove from the oven and spread the onions, carrots, celery, and garlic over the bones. Smear the tomato paste over the vegetables and return the pan to the oven. Roast for another 45 minutes. Remove from the oven and pour off the fat from the pan.
Transfer the bones and vegetables to a large stockpot. Do not discard the juices in the roasting pan. Add the water, bay leaves, thyme, salt, and peppercorns to the stockpot and bring to a boil.
Meanwhile, place the roasting pan over two burners on medium-high heat. Add the wine and stir with a heavy wooden spoon to deglaze and dislodge any browned bits clinging to the bottom of the pan. Add the contents to the stockpot. When the liquid returns to a boil, reduce the heat to low and simmer, uncovered, for 8 hours, skimming occasionally to remove any foam that rises to the surface.
Ladle through a fine-mesh strainer into a large clean pot. Bring to a boil, reduce to a gentle boil, and cook, uncovered, until reduced to 6 cups in volume, about 1 hour. Let cool, then cover and refrigerate overnight.
Remove any congealed fat from the surface of the stock. The stock can be stored, covered, in the refrigerator for up to 3 days, or frozen in airtight containers for up to 2 months.