Special equipment: a straight-sided 3-quart tall glass bowl or four 16-ounce wide-mouth glass jars with lids
Bring a small saucepan of water to a boil. Add the farro, and simmer until plumped and tender, 20 to 25 minutes. Drain and rinse under cold water. (The farro can be made and refrigerated up to 2 days ahead.)
Meanwhile, use a sharp knife to remove the peel and pith from the oranges. Cut the oranges into pieces, and remove the seeds.
Cook the pine nuts, raisins, capers, 2 tablespoons of the oil and the garlic in a small skillet over medium-high heat, swirling frequently, until the pine nuts and garlic are toasted and light brown and the raisins are browned in spots, 4 to 6 minutes. Add 1 tablespoon of the vinegar, and cook until just reduced, about 30 seconds. Remove from the heat, and let cool.
Whisk the remaining 3 tablespoons vinegar, the shallots, mustard, honey, 1/2 teaspoon salt and a few grinds of pepper in a medium bowl. Slowly drizzle in the remaining 1/3 cup oil, whisking constantly, until blended into a vinaigrette.
Using a 3-quart tall glass bowl for 1 large salad or four 16-ounce wide-mouth glass jars for 4 individual salads, make a first layer with half the mesclun, then add the following in separate layers: the oranges, radicchio, farro, the remaining mesclun, the beets and blue cheese. Top with the pine nut mixture.
If making 1 salad, just before serving, transfer it to a large bowl, toss with the vinaigrette and season with salt and pepper. If making 4 salads, add vinaigrette to each jar, season with salt and pepper, cover with the lid and shake to coat.
To achieve pretty, defined layers, be sure to layer more on the sides. It's OK if there isn't enough of an ingredient to fill the middle.