1Steam, cool and slice potatoes. Whisk together marinade ingredients in large nonreactive bowl. Add mushrooms and marinate at room temperature for 30 minutes. Cut mushrooms in thick slices and grill until cooked through. Heat 1 Tbsp. olive oil in skillet over medium heat. Add onions and sauté until deep golden. Preheat oven to 350. Whisk together salad dressing ingredients. Mix potatoes, mushrooms and onions in large nonreactive bowl. Stir in dressing, adding salt and pepper to taste. Heat in oven for about 20 minutes before serving. To serve, mound on a plate or shape in a ring mold. Make 4 to 6 servings.
Cooking the Costco Way