Preheat oven to 400 degrees.
In a large saucepan, combine broth, water, and barley. Season to taste, and bring to a boil. Cover and cook over low heat until the barley is nearly tender, about 18 minutes.
Meanwhile, in a large nonstick skillet, heat oil. Add mushrooms and shallot, season to taste, and cook over high heat until tender and browned, about 12 minutes.
In a medium bowl, combine the ground pork, egg, breadcrumbs, cheese, parsley, garlic, salt and pepper. Knead the mixture until blended; roll into small balls. Place meatballs on foil covered baking pan, and bake 12 minutes at 400 degrees, turning once.
Add the meatballs and mushrooms to the soup and simmer over moderate heat until the meatballs are cooked through and the barley is tender, about 8 additional minutes. 4 servings.