Start the sprouting process 2–4 days before making this salad. In a clean 1-quart canning jar, add 1/2 cup lentils and enough water to fill half the jar. Let sit overnight uncovered. Drain water and rinse lentils, leaving them in the jar. Cover the jar with a piece of cheesecloth, holding it in place with a lid ring or a rubber band. Lay the jar on its side on the counter, shaking the lentils to distribute them evenly. Once in the morning and once in the evening until ready to use, rinse the lentils. Sprouts will continue to grow for several weeks if well rinsed. To slow growth, put a sealed lid on the jar and refrigerate—they should keep for up to a week.
Preheat oven to 400°F. In a large roasting pan, spread the beets evenly and coat lightly with olive oil. Cook for about 15 minutes in oven, or until soft. Remove beets from pan and cool.
To make the vinaigrette, whisk together olive oil, lemon, capers, shallots, mustard, honey, half the fresh herbs, salt, and pepper in a large bowl. Set aside.
Dress sprouted lentils and beets with vinaigrette, sprinkle with remaining herbs and radicchio, and stir to incorporate. Season with salt and pepper to taste. This salad is delicious served immediately, and it tastes even better the next day after flavors have fully melded.