You could try other roots here as well, or combine several roots. Parsnips have a special affinity for lentils…

2 lbs beets
1 1/2 c green or brown lentils
2 carrots, (peeled) and finely diced
2 t dried thyme, or 2 T fresh thyme leaves
3 cloves garlic, peeled and crushed
salt and pepper, to taste
3 T red wine vinegar
8 T extra-virgin olive oil, divided
3 T lemon juice
chopped fresh parsley
1 small red onion, peeled and finely sliced
1 c  or more feta cheese, crumbled

1. Preheat oven to 350ºF. Put scrubbed beets in a baking dish, add some water (about 1/2 an inch in the dish), cover with foil and bake until tender–45 minutes to over an hour, depending on the size of the beets. Start checking at 45 minutes. Remove from oven and let cool.

2. Meanwhile, put lentils, carrots, thyme, and garlic  in a saucepan with water to cover.  Bring to the boil, then simmer for about 25 minutes or until the lentils are cooked. Don’t let them get mushy, you want them to hold their shape for the salad. Drain, if necessary, and put into a large serving bowl. Add salt, pepper, the red wine vinegar, and 4 tablespoons of the olive oil. Toss to combine.

3. Peel the cooled beets if you like. Cut into bite-sized pieces and add to lentil mixture. Add the lemon juice, remaining olive oil, parsley, onion, and feta. Gently toss. Taste for seasonings. Serve.