To make the dressing, finely mince the garlic and jalapeño (if using). Add to a serving bowl and whisk in the lime juice, mango juice, and olive oil. Season to taste with salt and pepper.
Add the arugula to the serving bowl and toss to combine with the dressing. Mix in the beans, and half of the avocado and mango. Top the salad with the remaining avocado and mango slices.