In a medium bowl, whisk the olive oil with the lemon juice and season with salt and pepper. Add the zucchini and toss well; let stand for 3 minutes. Arrange the zucchini slices, overlapping them slightly, on a platter. Add the arugula to the bowl and toss with the dressing, then mound on the zucchini. Scatter the Parmesan over the top and serve.
1/4 cup extra-virgin olive oil
2 tablespoons fresh lemon juice
Salt and freshly ground pepper
1 pound small green and yellow zucchini, sliced 1/8 inch thick on the diagonal with a mandoline
1 bunch arugula (1/4 pound), large stems discarded
1 ounce Parmesan, shaved (1 cup)