Prepare the Mushrooms
Place the dried porcini mushrooms in a bowl and pour over them two cups of boiling water. Let them sit for 30 minutes.
Set a strainer over a bowl, and line it with cheesecloth. Lift the mushrooms from the water and squeeze over the strainer, then rinse in several changes of water. Squeeze out the water and set aside.
Strain the soaking water through the cheesecloth-lined strainer. Add water as necessary to make a total of two cups. Set aside.
Make the Soup
Heat the oil in a large, heavy soup pot or Dutch oven over medium heat, and add the onion.
Cook, stirring often, until just about tender, about five minutes, and add the sliced fresh mushrooms.
Cook, stirring, until the mushrooms are beginning to soften, about three minutes, and add the garlic and ½ tsp salt.
Continue to cook for about five minutes, until the mix is juicy and fragrant.
Add the reconstituted dried mushrooms, the barley, the mushroom soaking liquid, and the chicken stock (or water if you’re using it instead). Salt to taste.
Add the bouquet garni. Bring to a boil, reduce the heat, cover and simmer 45 minutes. Meanwhile, stack the kale leaves in bunches and cut crosswise into slivers.
Add the kale to the simmering soup, and continue to simmer for another 15 to 20 minutes. (The barley should be tender and the broth aromatic. The kale should also be very tender)
Remove the bouquet garni, taste and adjust salt, add a generous amount of freshly ground pepper and serve.