4 medium beets, scrubbed and trimmed, leaving about 1 inch of stems attached
2 bunches mixed greens, coarse stems discarded, rinsed and spun dry (about 8 cups)
1 1/4 teaspoons Dijon mustard
2 tablespoons white-wine vinegar
1/4 teaspoon dried tarragon, crumbled
1/4 teaspoon salt
1/4 teaspoon freshly ground black pepper
1/4 cup plus 2 tablespoons extra-virgin olive oil
3/4 cup fresh bread crumbs
1/2 teaspoon dried tarragon, crumbled
3/4 teaspoon salt
1/8 teaspoon freshly ground black pepper
8 ounces Montrachet or other soft goat cheese, cut into eight 1/2-inch rounds and chilled, covered
Preheat oven to 400°F. Wrap beets tightly in foil and roast in middle of oven 1 to 1 1/2 hours, or until tender. Unwrap beets carefully and cool until they can be handled. Discard stems and peel beets. Beets may be prepared up to this point 1 day ahead and chilled, covered. Cut each beet into 8 wedges and cover.
Blend together mustard, vinegar, tarragon, salt, and pepper. With motor running add oil in a stream and blend until emulsified. Vinaigrette may be made 1 day ahead and chilled, covered.
In a bowl stir together breadcrumbs, tarragon, salt, and pepper. Cut each cheese round in half crosswise. Coat each piece of cheese evenly with crumb mixture, pressing gently, and transfer to a baking sheet. Goat cheese may be prepared up to this point 1 day ahead and chilled, covered loosely. Let cheese come to room temperature before proceeding. Preheat broiler.
Broil goat cheese about 2 inches from heat until crumbs are lightly browned, about 2 minutes. In a bowl toss mixed greens and onion with half of vinaigrette. Arrange greens, beets, and goat cheese on 8 salad plates and drizzle remaining vinaigrette over beets.