Preheat oven to 400 F.

Lay piece of parchment in shallow baking dish. Place beets on top of parchment, pierce with fork, and season with 1/4 tsp salt, 1/4 tsp pepper, and olive oil. Wrap beets tightly in parchment and roast for 50 to 60 minutes until tender. Rest in parchment for 30 minutes, or until cool enough to handle. Unwrap beets and remove skins with knife, then cut into segments.

In Mason jar fitted with lid, combine kefir, honey, vinegar, orange zest, gingerroot, and remaining 1/4 tsp salt and 1/4 tsp pepper. Set aside in refrigerator.

Use food processor on pulse setting to chop pistachios until size of small peas. Set aside.

With knife, remove peel and pith from oranges. Cut along division of orange to segment. Once all segments have been removed, squeeze remaining orange in bowl to capture juice. Repeat with second orange. Reserve.

To assemble salad, arrange beet segments and orange slices over arugula. Add 2 Tbsp reserved orange juice to dressing and mix well. Drizzle approximately 3 Tbsp dressing over salad. Toss and top with pistachios.