Fill a medium saucepan with water and salt the water generously. Bring the water to a boil over high heat. Add the lentils and stir so they don’t stick to the bottom. Turn the heat down to medium and cook the lentils about 20 minutes, until tender. Drain the lentils and rinse them in cold water to cool. Refrigerate until ready to use.
To make the dressing: add the oil, vinegar, tahini, mustard, maple syrup, garlic, and salt in a small mixing bowl. Whisk together until smooth and combined.
To assemble the salad: place the greens on a serving plate. Top with lentils and beets. Sprinkle crumbled goat cheese over everything. Drizzle with tahini dressing.