Season the chicken breast evenly with half of the sea salt, black pepper, and dried oregano.
Preheat a grill pan or skillet over medium-high heat and cook the chicken for 6-7 minutes per side until the internal temperature reaches 165 degrees Fahrenheit.
Remove the chicken from the heat and let it rest for 5 minutes before slicing it into small, bite-sized cubes.
In a large mixing bowl, combine the rinsed chickpeas, red kidney beans, and black beans.
Add the diced red bell pepper, finely diced red onion, and chopped fresh parsley to the bean mixture.
In a small glass jar or bowl, whisk together the extra virgin olive oil, fresh lemon juice, and the remaining salt, pepper, and oregano.
Pour the lemon-herb vinaigrette over the salad and toss thoroughly to ensure all ingredients are well-coated.
Gently fold in the grilled chicken cubes and serve immediately or refrigerate for 30 minutes to allow the flavors to meld.