Heat oven to 425°F. Toss the diced beets with the roasting olive oil and ½ teaspoon salt. Spread in a single layer and roast 25 minutes, flipping halfway, until tender with caramelized edges.
Tip the hot beets straight into a large bowl, add the white wine vinegar, and toss. Let cool to warm or room temperature, about 15 minutes.
Add the honey, lemon juice, garlic, lemon zest, and extra-virgin olive oil to the beets. Season with salt and pepper and toss.
Fold in the pistachios and Parmesan.
Pile the arugula on a platter and spoon the beets and their dressing over the top. Finish with an extra squeeze of lemon if you like.
