Before I put the ingredients in the slow cooker, I do some prep work.
1. In a bowl, soften the mushrooms by pouring boiling water over them and let soak for about 10 minutes. Drain the mushrooms but save the liquid. Strain it through a cheesecloth to get rid of any dirt or sand. Set aside.
2. In a skillet, brown the soup bone on both sides in a tiny bit of oil. Drain on a paper towel and set aside.
3. Cut off the dark green parts of the leek (use in making chicken or vegetable broth or discard) and use only white and light green parts. Slice the leek in half lengthwise and wash very carefully in between the leaves. Dry with paper towel. Chop the leek finely. (You can substitute onion for the leek.)
4. Put a bit of oil in a skillet (use the one in which you browned the bone), add the diced veggies and saute on medium heat until the vegetables are fragrant and the leeks are translucent, about 10 minutes.
5. Now you are ready to put everything in the slow cooker. Add the pearl barley and the seasonings. Pour 8 cups or so of water (including the saved mushroom soaking liquid) over everything, cover, set on high, and cook until the meat is just falling off the bone, about 4 hours.
6. Discard the bone. Dice the meat and put it back in the soup. Adjust seasoning if needed.
The soup will be thick with the barley and, as a bonus - if you like, you will have the marrow to smear on a slice of bread, sprinkle with salt and pepper and enjoy!
When serving, sprinkle some fresh chopped parsley over the soup for color and even more flavor.
A steaming bowl of this soup, some crusty bread and a green salad...the best comfort food I know! Enjoy!