Place the lentils in a saucepan with water and bring to a boil. Reduce heat to medium and simmer for 30-35 minutes.
Drain lentils and cool them with cold water. Allow lentils to drain well. Place them in a large serving bowl and add the tomatoes, onion, parsley, mint and set aside.
Prepare the dressing by placing all the ingredients in a jar. Cover and shake vigorously.
Drizzle the salad with the dressing and gently toss. Refrigerate the tabbouleh for 30 minutes to absorb all the flavors of the herbs and spices. Sprinkle with feta cheese and serve.