Begin port reduction, if using: In a small saucepan over low heat bring port to a slow boil, reduce heat and simmer until syrupy and sweet, and reduced to 1/2 cup, at least 30 minutes, checking from time to time.
Meanwhile, in a saucepan heat 1 tablespoon oil, add onion and cook until tender and golden. Add barley and stir to coat completely in oil. Add just enough mushroom stock to cover and bring to a boil, stirring constantly. Reduce heat and simmer, stirring constantly. Add more stock, 1/2 to 1 cup at a time, as liquid is absorbed. Continue adding liquid until barley is tender, tasting frequently. When barley is done, it should be slightly soupy, like a risotto. Continue with remaining recipe steps while barley cooks.
In a separate sauté pan heat remaining oil, add sliced mushrooms and sauté until lightly browned and tender; season with salt and pepper. Add tomatoes and cook 2 minutes more.
Preheat barbecue, grill or stovetop grill over high heat. Brush portobello mushrooms with oil and grill, turning once, until tender and grill marks appear on cap.
To finish, stir mushroom-tomato mixture into barley. Vigorously stir in butter and cream. Stir in Parmesan and basil. Using grilled mushroom as a cup, mound barley "risotto" in center and sprinkle with parsnip strips, if using. Sprinkle with extra Parmesan and basil. Drizzle with port reduction and serve immediately.
Yield: 2 servings