Rinse the lentils under cold water and add them to a saucepan. Cover with double the water, bring to a boil, and reduce the heat to simmer for about 20 minutes, or until tender. Drain and set aside.
In a large mixing bowl, combine the baby spinach, diced cucumber, and finely chopped red onion.
In a small bowl, whisk together the olive oil, lime juice, ground cumin, salt, and pepper until well blended.
Add the cooked lentils to the salad mixture and pour the cumin-lime dressing over it. Toss gently to combine and coat all the ingredients evenly.
Fold in the chopped mint leaves. Taste and adjust seasoning if necessary.
Serve the salad with lime wedges on the side, and add optional toppings like feta cheese or cherry tomatoes if desired. Enjoy!
