1Preheat the oven to 400°F. Place the beets in an 8-inch square baking dish and add just enough water to cover the bottom of the dish (about 1/3 cup). Drizzle the beets with olive oil and sprinkle with salt and pepper. Cover the dish tightly with aluminum foil. Bake until a knife can be easily inserted into the center of the beets, about 40 minutes to 1 hour 10 minutes (for small beets start checking after 40 minutes; large beets may need even longer than 70 minutes).
2To make the vinaigrette, in a bowl, whisk together the vinegar, mustard, shallot, and a pinch each of salt and pepper. Let sit for 15 minutes, then whisk in the olive oil in a slow and steady stream; set aside.
3When the beets are ready, carefully remove the foil and let them sit until cool enough to handle. Peel and the beets. Cut them into wedges, place them in a bowl, and drizzle them with a little vinaigrette. Season with a little salt and pepper.
4Add the greens to a shallow serving bowl. Drizzle with a little vinaigrette and toss to coat. Top with the beets, pistachios and cheese. Serve.