To prep the oranges, cut off the tops and bottoms, then trim away the white pith and peel, starting from the top and following the curve of the fruit. Slice the oranges into rounds. In a bowl, toss together the oranges, beets, farro, a splash of the vinaigrette, and a pinch of salt. Cut the Humboldt Fog cheese into small slices for serving.
Place the baby lettuces in a large bowl, drizzle with some of the remaining vinaigrette, season with salt and freshly ground pepper, and toss to coat. Fold in the oranges, beets, farro, and hazelnuts. Heap the salad on plates, top each with a few slices of the Humboldt Fog, and serve.