Combine cooked black beans, sliced scallions, diced cucumbers, diced tomatoes, and halved celery in a large bowl.

In a separate bowl, whisk together olive oil, lemon juice, orange zest, and basil.

Pour the dressing over the black bean mixture and toss gently to combine.

Season with salt and black pepper to taste.

Cover the bowl and let it rest at room temperature for at least 1 hour to allow the flavors to meld before serving.