Preheat the oven to 450°F (232°C).

Wrap the beets in foil.

Roast the beets for about 1 hour, or until tender.

Let the beets cool until they are cool enough to handle.

Slip the skins off the beets.

Cut the beets into wedges.

Tear the beet greens into bite-size pieces (about 2 cups).

In a medium saucepan, bring water to a boil.

Add the lentils and cook until tender, about 20 minutes.

Drain the lentils and cool under running water.

Drain the lentils well.

In a large bowl, whisk together the olive oil, Dijon mustard, lemon juice, and scallions.

Add the lentils, beets, and beet greens to the bowl.

Season with salt and pepper.

Toss the salad and serve immediately.