Split the lettuce between 4 salad bowls or plates. Equally divide the shrimp, cucumber, avocado, tomatoes and black beans over the lettuce. Alternatively, you can do this in one large salad bowl.
To make the dressing, place the fresh cilantro, lime juice, white vinegar, ground cumin, salt and pepper in a small bowl. Mix well to combine and drizzle over the salad and serve.