Makes 2 to 3 cups

INGREDIENTS

• 2 ounces dried porcini mushrooms
• 2 cups boiling water
• ¼ pound thick-sliced bacon, cut into ½-inch-wide strips
• ½ cup thinly sliced shallots
• 3 tablespoons thinly sliced garlic
• ½ pound white or cremini mushrooms, thinly sliced
• 1 750-ml bottle fruity red wine, such as Zinfandel
• 5 cups homemade beef stock or canned low-sodium chicken broth
• 1 fresh rosemary sprig
• Salt and freshly ground black pepper
• 4 tablespoons (½ stick) butter, cut into 4 pieces

INSTRUCTIONS

1. Place the dried porcini mushrooms in a small bowl and cover with the boiling water. Soak for at least 45 minutes, or up to several hours, until soft.
2. Remove the porcini from the liquid with a slotted spoon. Chop and set aside. Strain the soaking liquid, leaving behind any grit in the bottom of the bowl, and reserve.
3. Heat a large saucepan over medium heat. Fry the bacon until golden but not quite crisp. Leave about 2 tablespoons of the fat in the pan with the bacon; save the rest of the fat for another purpose or discard.
4. Add the shallots and garlic to the pan, cover, and cook until soft, stirring from time to time, about 3 minutes. Stir in the fresh mushrooms and cook until soft, 5 to 7 minutes, scraping up any browned bits from the bottom of the pan.
5. Add the chopped porcini mushrooms and red wine to the pan, bring to a boil, and boil until reduced to about 1 cup, about 15 minutes.
6. Add the reserved porcini soaking liquid and the beef stock or chicken broth to the pan and continue to boil until the sauce is reduced to 5 cups, about 30 minutes. Skim off any fat or scum from the surface of the sauce, add the rosemary, and cook for 3 minutes more. Remove the rosemary, cover, and set the sauce aside.
7. While the roast is resting, pour off all the fat from the roasting pan, leaving the juices in the pan. Place the pan over two burners on medium heat and add the sauce. Bring to a boil, scraping up any browned bits from the bottom of the roasting pan.
8. Pour the sauce back into the saucepan and boil until the sauce develops a rich, meaty flavor and is just turning syrupy. There should be about 3 cups of jus.
9. Season the sauce to taste with salt and freshly ground black pepper.
10. Whisk in the butter 1 tablespoon at a time just until it is melted and the sauce becomes velvety.
11. Serve the sauce immediately over your favorite meat dish.