Season the chicken breast with half of the sea salt and black pepper.
Grill or pan-sear the chicken over medium-high heat until the internal temperature reaches 165°F, then let it rest for 5 minutes before dicing into bite-sized pieces.
Rinse and drain the chickpeas and cannellini beans thoroughly under cold water.
In a large mixing bowl, combine the beans, diced cucumber, halved cherry tomatoes, and finely diced red onion.
In a separate small jar or bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, and the remaining sea salt and black pepper.
Add the diced chicken to the bean and vegetable mixture.
Pour the lemon-herb vinaigrette over the salad and toss well to ensure every ingredient is evenly coated.
Finish by folding in the freshly chopped parsley and serve immediately or chill for 30 minutes to allow flavors to meld.