Start by rinsing the red lentils under cold water to remove any debris. In a medium saucepan, combine the lentils with 3 cups of water and bring to a boil. Reduce the heat to medium-low and simmer for 15-20 minutes until tender. Drain and cool.

In a large mixing bowl, add diced cucumber, grated carrot, finely chopped onion, along with chopped parsley and mint.

In a small bowl, whisk together olive oil, lemon juice, and balsamic vinegar. Season with cumin, salt, and pepper to taste.

Once the lentils are cooled, add them to the bowl with the vegetables. Pour the dressing over and gently toss to combine.

Crumble feta cheese into the salad and gently fold it into the mixture, being careful not to break it down too much.

Cover the salad and chill in the refrigerator for at least 30 minutes before serving.