Recipe Instructions Cook's Notes: You can substitute other dried mushrooms for the porcinis; if using shiitakes, discard their tough stems after soaking. Use steaks such as rib-eye, top loin (New York) or tenderloin. For nonalcoholic options, use broth, tomato juice or fruit juice. Cover the mushrooms with hot water and soak for 30 minutes. If you'd like to enrich the sauce with butter, cut 1 to 2 tablespoons of butter in 1/2-tablespoon pieces and refrigerate them. Heat the oven to 180 degrees or its lowest setting. Remove the mushrooms from the water and cut in 1/2-inch pieces. Place them in a saucepan with the stock and thyme. Bring to a boil. Simmer uncovered until the mixture is reduced to about 1 cup, about 10 minutes. Cover and reserve. Pat the steaks dry. Trim the fat from their edges. Sprinkle them with salt and pepper on both sides. In a large heavy skillet, heat the oil and 1 tablespoon of butter over medium-high heat until the butter melts and its foam begins to subside. Add the steaks and cook the first side for 2 or 3 minutes, regulating the heat so the fat does not burn. Turn the steaks and cook until done to your taste, about 2 or 3 minutes. To check for doneness, press a steak with your finger: If the meat does not resist, it is rare; if it resists slightly, it is medium-rare. (If you are not sure, make a small cut in its thickest part and check its color inside.) Immediately transfer to an ovenproof platter and keep them in the oven. Note: If you don't have a large skillet, use 2 skillets to cook the steaks, cook the shallots and deglaze with the wine. Then pour the wine into 1 skillet, reduce it to 1/4 cup and continue. Pour off the fat from the skillet, and melt 1 tablespoon of butter over medium-low heat. Add the shallots and cook, stirring, 1 minute. Add the wine and bring to a boil over high heat, stirring and scraping up any brown bits. Boil the wine, stirring often, until reduced to about 1/4 cup, about 2 minutes. Pour the wine into the porcini mixture and bring to a simmer over medium heat. To thicken the sauce, put the potato starch in a small bowl and stir in 1 tablespoon of water until blended. Gradually whisk half of the potato starch slurry into the simmering sauce. Return to a boil, stirring. For a thicker sauce, gradually stir in the remaining slurry and return to a boil. To enrich the sauce with butter, reduce the heat to low and add the cold butter pieces one by one, shaking the saucepan to blend them into the sauce. Off the heat, stir in the parsley, chives and/or tarragon. Taste and adjust seasoning; if necessary, add sugar to balance the wine's acidity. Spoon the sauce over or around the steaks and serve. This recipe yields 4 servings. Each serving: 576 calories; 244 mg sodium; 136 mg cholesterol; 45 grams fat; 18 grams saturated fat; 2 grams carbohydrates; 35 grams protein; 0.17 gram fiber.