1) Preheat the oven to 190C/Gas 5.
2) Place a large sheet of aluminium foil on a baking tin. Place the beetroot on top, drizzle with the olive oil and sprinkle with salt, then fold the long and short edges of the aluminium foil up to the middle and roll together, making a packet with the beetroot inside. Put in the oven and roast until fork-tender, about 1 1/2 hours. (Can be done a day or two ahead of time.) Allow to cool, then slip the skins from the beetroot, trim the ends, and cut into 1-cm cubes. Set aside.
3) Quarter the chicory lengthwise, then slice crosswise into 1-cm thick moons. Combine the beetroot and chicory in a salad bowl and toss with the Garlic an herb vinaigrette. Season with additional salt and pepper, if necessary. Serve immediately.
For the garlic and herb vinaigrette:
1) In a small glass bowl, dissolve the salt in the vinegar, then add the pepper, shallot, garlic, mustard, and herbs and combine well.
2) Whisk in the olive oil in slow, steady stream until the dressing is thickened. Alternatively, place all ingredients in a glass jar, close the lid, and shake vigorously.