1. Place the barley into a medium pot. Add 3 cups chicken stock or broth. Bring to a boil. Turn down to a simmer and cook, uncovered, for 20-25 minutes, stirring occasionally to make sure it is not burning or sticking, especially at the end of the cooking time. The barley is done when the grains are plump and all broth is absorbed. Remove from heat.2. Meanwhile, in a large pot, heat the olive oil over medium heat. Add the flanken. Sear for 3-4 minutes, until brown. Using tongs, turn each strip over and sear on the other side until brown. Remove from the pot.3. Place the shallots into the pot and use a wooden spoon to help scrape up all the good browned bits that the beef left behind. Cook until the shallots are shiny, about 3 minutes. Add the garlic and sugar. Stir well and cook for 3 minutes longer, until the garlic is fragrant.4. Add the mushrooms and Dijon mustard. Crumble in the dried thyme. Stir. Allow the mushrooms to cook for 4 minutes, until shiny and beginning to release some of their liquid.5. Add the margarine and allow it to melt into the mushrooms. Stir.6. Sprinkle the flour over the mushrooms. Mix until the mushrooms and shallots become sticky and look dry.7. Pour in the beef stock or broth, the cooking sherry, and the remaining cup for chicken stock or broth. Stir. Bring to a simmer.8. Once the stock or broth is simmering, cut the flanken between each bone. Add the meat back into the pot. Cover and turn the heat down to a simmer. Cook for 30 minutes.9. Spoon a portion of the barley into each bowl. Ladle the soup over the barley.SOURCE: Kosher by Design: Teens and 20-Somethings, by Susie Fishbein. Recipe reprinted with permission from Mesorah Publications.