1. Prepare the beans: In a large mixing bowl, combine the chickpeas, kidney beans, and black beans. Make sure they are well-drained and rinsed to remove any excess sodium.

2. Add the vegetables: To the bowl with the beans, add the diced cucumber, halved cherry tomatoes, and finely chopped red onion. Gently toss the ingredients together to combine.

3. Make the dressing: In a small bowl, whisk together the olive oil, red wine vinegar, dried oregano, salt, and pepper. Adjust the seasoning to taste, ensuring the dressing is flavorful but not overpowering.

4. Marinate the salad: Pour the dressing over the bean and vegetable mixture. Toss everything together until the salad is evenly coated with the dressing. Allow the salad to marinate for at least 15-30 minutes at room temperature, or refrigerate for up to 2 hours to enhance the flavors.

5. Serve: Before serving, give the salad a gentle toss. Transfer it to a serving bowl or plate. Garnish with fresh parsley and arrange lemon slices on top for a vibrant presentation.

6. Enjoy: This Easy Greek Bean Salad can be served as a refreshing side dish or a light main course. It pairs well with grilled meats or can be enjoyed on its own for a healthy meal.