Preheat oven to 375 degrees F. Heat large sauti pan over medium flame, add oil and onion and sauti until onions are translucent, about four minutes. Add tomato paste and sauti until deep brown. Add mushrooms and sauti until well browned and there is no liquid in the pan. Add barley, crushed tomatoes, vegetable stock, and porcini mushrooms. When adding the porcini, pour in the liquid, taking care to leave out any sediment that may have settled. Stir to combine. Add rosemary, thyme, salt and pepper. Pour into a two-quart baking dish and set aside.
To make topping, press potatoes through a ricer or food mill into a large mixing bowl. Add goat cheese and buttermilk and stir until fluffy. Add additional buttermilk if consistency is too dry. Spoon onto mushroom mixture, leaving lots of hills and valleys for melted butter to run over. Drizzle with the truffle oil or melted butter and bake until potatoes are golden, around 30-40 minutes. Remove from oven and let rest for about five minutes before serving.
Serves 6 to 8
Recipe used with permission from Janine MacLachlan, chef and owner of The Rustic Kitchen cooking school in Chicago, IL.