3 cups Pinot Noir, Cabernet Sauvignon, or other good-quality, robust red wine
3 tablespoons butter, divided
2 shallots, minced
1/2 tablespoon freshly crushed black peppercorns
1/2 cup brandy
1/2 cup heavy cream
1/2 cup beef stock
Salt to taste
To prepare the sauce, pour the wine into a nonreactive saucepan and bring to a boil. Let reduce over medium-high heat until about 1/2 cup remains, about 20 minutes. Meanwhile, heat 2 tablespoons of the butter in a small heavy saucepan and sauté the shallots and peppercorns over medium heat for 2 minutes. Add the brandy, carefully ignite, and let flame for 3 or 4 minutes until the alcohol is burned off. Continue cooking for 2 to 3 minutes, until the pan is almost dry. Add the cream, turn up the heat to medium-high, and cook for 3 minutes. Stir in the reduced wine and cook over medium heat for 10 minutes longer. Stir in the remaining 1 tablespoon of butter, season with salt, and simmer until 1 cup remains, about 10 minutes more.
Meanwhile, bring the steaks to room temperature and brush both sides with the mustard. Combine the peppercorns and salt on the plate and roll the steaks in the mixture, pressing to coat each side well. Grill the steaks over direct medium-high heat for about 5 minutes per side for medium-rare, 6 to 7 minutes for medium, or to the desired doneness. Transfer to serving plates and spoon with the warm sauce over steaks.