In a large serving bowl, place the cooled lentils on the bottom, top with the cucumber, red onion, and half of the crumbled feta.
Blend the dressing one more time to ensure all the ingredients are well incorporated, and then pour about half of the dressing over the salad. Gently toss to combine. Determine if you need more dressing and season with salt and pepper if needed.
Top the salad with the remaining feta cheese and chopped cilantro, and serve.