Rinse the lentils under cold water. In a pot, combine lentils and water. Bring to a boil, then reduce heat and simmer for 15-20 minutes until tender but not mushy. Drain and let cool.

In a large bowl, combine the cooled lentils, cucumber, red bell pepper, red onion, cherry tomatoes, parsley, and mint.

In a small bowl, whisk together olive oil, lemon juice, minced garlic, cumin, salt, and black pepper to make the dressing.

Pour the dressing over the lentil mixture and toss gently to combine.

Sprinkle crumbled feta cheese on top if using.

Let the salad sit for at least 10 minutes before serving to allow flavors to meld. Serve chilled or at room temperature.