We rinse off our mango and then cut down each side of the large pit. We peel and chop each piece, yielding ½ cup plus 2 tablespoons of mango. We add the mango to the blender. Next, we rinse 3 of our limes and halve. We squeeze them into a measuring cup. We want ¼ cup of lime juice. In the measuring cup, we also add the oil, garlic, jalapeño, cumin, and a pinch of salt and some freshly ground black pepper. We add this to the blender.
We blend until smooth. We taste for seasoning and pour into the rinsed out measuring cup. We have 1-cup of dressing. We refrigerate covered with plastic until we are ready to use (it keeps for a couple of days).
When we are almost ready to eat, we add the black beans to a large bowl.
We rinse the avocado and then slice in half. We remove the pit carefully with our knife, peel, and dice.
We rinse and halve our fourth lime and then squeeze some lime onto the avocado and sprinkle with a little salt. We also rinse our tomato and chop, removing the seeds as much as possible. We sprinkle the tomato with salt as well.
We add the avocado, tomato, about a ½ cup of scallions, and the cilantro to the beans. We stir the reserved dressing and toss the beans with a little less than half of the dressing to start. We taste for seasoning, add a little more dressing, and serve. The remaining dressing we store in the fridge.