How to Make It
Preheat the oven to 500°. In a small baking dish, toss the beets with 2 tablespoons of the vinegar and the water. Cover with foil and bake for 1 hour, or until tender. Let cool, then peel the beets and cut them into 1/4-inch wedges. Reduce the oven temperature to 350°.
In a small bowl, toss the hazelnuts with the simple syrup and 3/4 teaspoon each of salt and pepper. Transfer to a parchment-lined baking sheet and bake for 25 minutes, or until the syrup-covered nuts are shiny and dry. Let cool. Leave the oven on.
Brush both sides of the baguette slices with 2 tablespoons of the olive oil. Arrange on a baking sheet and bake for 10 minutes, or until lightly toasted. Let cool, then spread with the blue cheese.
In a large bowl, whisk the remaining 2 tablespoons of vinegar and 6 tablespoons of olive oil until blended. Season with salt and pepper. Add the mesclun, herbs, beets and hazelnuts; toss to coat. Transfer the salad to plates and serve with the Roquefort toasts.
To make simple syrup, combine equal parts of sugar and water and simmer over moderate heat to dissolve the sugar. Refrigerate any leftover syrup.