Start by rinsing and cooking your lentils until tender but not mushy. Drain and let them cool.
Dice the cucumbers, tomatoes, red onions, and bell pepper into small bite-sized pieces.
In a small bowl, whisk together olive oil, lemon juice, minced garlic, salt, pepper, and oregano.
In a large mixing bowl, combine the lentils, chopped veggies, olives, mint and parsley. Pour the dressing over the top and toss gently to combine. Add feta cheese if desired.
Let the salad chill for at least 30 minutes to allow flavors to marry. Serve cold or at room temperature.