In a large bowl, whisk olive oil, vinegar, mustard, honey, oregano, salt, and pepper. Stir in feta until creamy.
Add lentils and toss to coat. Let sit for a few minutes to marinate.
Add beets, clementines, walnuts, and parsley. Toss gently to combine.
Serve immediately or refrigerate for up to 3 days. Garnish with extra feta or pomegranate seeds before serving.
