Place lentils in a small saucepan. Add water; bring to a boil. Reduce heat; simmer, covered, 20-25 minutes or until tender. Drain and rinse in cold water.
Transfer to a large bowl. Add mushrooms, cucumber, zucchini, onion and tomatoes. In a small bowl, whisk vinegar, mint, oil, honey, basil and oregano. Drizzle over lentil mixture; toss to coat. Add spinach, cheese and, if desired, bacon; toss to combine.