In a bowl combine the frisee, the radicchio, and the pears. In a small bowl whisk together the vinegar, the mustard, and salt and pepper to taste, add the oils in a stream, whisking, and whisk the dressing until it is emulsified. Toss the salad with the dressing, divide it among 8 salad plates, and sprinkle each serving with some of the hazelnuts. To toast and skin hazelnuts: Toast the hazelnuts in one layer in a baking pan in a preheated 350F. oven for 10 to 15 minutes, or until they are colored lightly and the skins blister. Wrap the nuts in a kitchen towel and let them steam for 1 minute. Rub the nuts in the towel to remove the skins and let them cool. Serves 8. Gourmet October 1990