Preheat the oven to 400° Fahrenheit. Place two pieces of aluminum foil and a sheet of parchment paper on a small baking sheet. Set aside.
Trim the tops of the beets just below the stems and trim off the skinny root end. Give the beets a good rinse to remove any dirt. Pat them dry.
Drizzle a bit of oil on the parchment paper and place the beets flat-side down clustered together in the oil. Drizzle a bit more oil over the tops and sprinkle generously with salt. Wrap the beets with parchment paper and aluminum foil to create an enclosed packet.
Place the wrapped beets on the baking sheet in the preheated oven and roast for 45 minutes. The beets should be fork-tender when done. Remove from the oven, carefully unwrap, and allow to cool enough to handle.
While the beets are roasting, cook the lentils. Add the lentils to a medium pot and cover with a couple of inches of water. Bring to a boil, then cover and reduce heat to a simmer. Cook the lentils for 15-20 minutes, until tender but not mushy. Drain the lentils and return to the pot.
Make the vinaigrette by combining the olive oil, orange juice and zest, balsamic vinegar, Dijon mustard, garlic, salt, and pepper in a small canning jar. Secure the lid and shake vigorously to combine.
Toss the still-hot lentils with ½ cup of the vinaigrette and let cool to room temperature.
Prepare the rest of the salad by peeling and grating the carrot, mincing the herbs, and roughly chopping the pistachios.
Once the beets are cool enough to handle, take a paper towel and rub the skin away from the beets. It should come off easily. Dice the peeled beets into a ½-inch dice.
Combine all the salad ingredients in a large bowl and toss. Add more vinaigrette, if desired, and adjust salt and pepper, to taste.
Serve immediately or store in the fridge until ready to serve. The flavors only get better as they sit, so this is a perfect dish to make ahead. Leftovers can be stored in the fridge for up to 4 days.