Preheat oven to 350o F. On a baking pan or cookie sheet, place walnuts in the oven for 6-8 minutes or until lightly toasted. While the walnuts are toasting, remove the root from each leek with a chef’s knife, and cut the remaining portion in half. Slice the leeks into 1/2-inch pieces; place in a small bowl, and submerge in water. Agitate the leeks to remove the dirt from the layers; drain liquid off and reserve leeks. Once the walnuts are toasted, remove from oven, and set aside.
In a large sauté pan over medium-high heat, add 1 tablespoon butter and cook until the aroma is nutty, and the butter looks slightly amber in color. Remove from heat, and place cooked butter in a small kitchen bowl. Using the same large sauté pan, add leeks, the remaining tablespoon of butter, 1 cup of water and a pinch of salt and pepper. Place over medium-high heat and cook for about 15-20 minutes, or until all the liquid has evaporated and the leeks are tender.
While the leeks are cooking prepare the barley. Heat a small-medium saucepot over medium heat. Add 1 tablespoon butter, then add barley. Cook for 1 minute, stirring to ensure the grains toast evenly. Add 2 1/2 cups of water, a pinch of salt and pepper, and turn the heat to high. Bring the water to a boil, and lower heat to medium-low. Cover, and cook until tender, about 12-15 minutes. Once the barley has absorbed the liquid, remove from heat, and reserve.
Add mushrooms and thyme to the pan with the leeks, and continue to cook over medium-high heat for 4-5 more minutes while stirring. Add the sherry vinegar, lemon juice and lemon zest to the bowl of melted butter, and whisk to combine. Once the mushrooms and leeks have cooked, over medium-high heat, add cooked barley and lemon-butter mixture to pan. Cook for 2-3 minutes while stirring to thoroughly incorporate. Remove pan from heat, remove thyme sprigs from pan, and discard. Season with salt and pepper.
Divide the barley onto two plates, and top with walnuts and Parmesan cheese. Enjoy!
