For Dressing: Cook bacon in heavy large skillet over medium heat until crisp. Using slotted spoon, transfer bacon to paper towels. Pour off drippings and reserve. Combine 1/4 cup reserved drippings with remaining ingredients in small bowl. Season to taste with salt and pepper. For Salad: Working over small bowl and using small sharp knife, cut between membranes of oranges to release segments; add to bowl. Tear spinach and radicchio into bite-size pieces and place in large bowl. (Can be prepared 1 day ahead. Cover dressing, orange segments, greens and reserved bacon drippings separately and refrigerate.) Drain orange segments. Heat 2 tablespoons reserved bacon drippings in heavy large skillet over medium-high heat. Add shiitake mushrooms and saute 1 minute. Add oyster mushrooms and season with salt and pepper. Saute until golden brown, about 2 minutes. Add mushrooms to greens and toss. Pour dressing into same skillet and boil 2 minutes. Pour dressing over greens. Add bacon, orange segments and chopped hazelnuts. Toss to combine. Season to taste with salt and pepper. Garnish salad with enoki mushrooms and serve. Serves 4 to 6. Bon Appetit March 1992