Cook the Lentils:

1. Rinse the lentils under cold water.
2. In a medium pot, bring 3 cups of water or vegetable broth to a boil.
3. Add the lentils and salt, reduce heat to a simmer, and cook for 18-20 minutes, or until tender but not mushy.
4. Drain and let cool completely.

Prepare the Dressing:

1. In a small bowl or jar, whisk together olive oil, lemon juice, red wine vinegar, Dijon mustard, garlic, oregano, and black pepper.

Assemble the Salad:

1. In a large bowl, combine cooled lentils, cherry tomatoes, cucumber, red onion, feta cheese, parsley, mint, and olives.
2. Drizzle the dressing over the salad and toss well to combine.

Chill & Serve:

1. Let the salad sit for at least 15-30 minutes for flavors to meld.
2. Serve chilled or at room temperature.