How to Make It
Preheat the oven to 350°. Spread the walnuts in a pie plate and toast for 8 minutes, until fragrant. Let the walnuts cool, then coarsely chop them.
Increase the oven temperature to 450°. On a rimmed baking sheet, toss the onion wedges with 1 tablespoon of the olive oil and season with salt. Roast the onions for about 25 minutes, turning once, until tender and browned in spots. Let the onion wedges cool to room temperature.
Meanwhile, in a large saucepan, cover the beets with water and bring to a boil. Simmer the beets over moderately high heat until almost tender, about 25 minutes; drain and let cool slightly.
Peel the beets and cut each one into 6 wedges. Transfer the beets to a small baking dish and toss them with 1 tablespoon of the olive oil and the balsamic vinegar and brown sugar; season with salt. Roast the beets for about 15 minutes, turning once, until tender. Let the beets cool to room temperature.
In a small bowl, toss the sliced pear with 1 tablespoon of the lemon juice. In a large bowl, toss the radicchio and endive with the remaining 2 tablespoons of olive oil and 1 tablespoon of lemon juice; season with salt and pepper. Mound the salad on plates and top with the walnuts, onions, beets, pears and Roquefort. Drizzle with olive oil and serve.