How to Make It
Preheat the oven to 400°. Put the beets and turnips on one large rimmed baking sheet and the parsnips and celery root on another. Sprinkle with the rosemary and drizzle 1 1/2 tablespoons of the olive oil over each pan of vegetables; toss well. Arrange the vegetables in an even layer and season with salt and pepper. Bake in the upper and lower thirds of the oven for about 35 minutes, until the vegetables are tender and golden brown. Switch the pans halfway through baking. Let cool slightly.
In a bowl, mix the remaining 1/4 cup of olive oil with the shallot, orange juice, vinegar and honey and season with salt and pepper.
Transfer the roasted vegetables to a medium bowl. Add the vinaigrette and mizuna, toss well and serve.