In a small bowl, mash one of the diced avocados with a fork until mostly smooth with a few small chunks remaining. Stir in the mayonnaise and fresh lime juice to create a creamy avocado dressing.
Season the dressing with cumin, salt, and black pepper. Mix until everything is well combined.
Place the diced cooked chicken breast in a large bowl. Pour the avocado dressing over the chicken and toss until every piece is fully coated.
Fold in the remaining diced avocado, red onion, and minced jalapeño. Stir gently so the avocado chunks stay intact and don't get smashed.
Sprinkle in the chopped fresh cilantro and give the salad one final gentle fold.
Serve immediately or cover tightly with plastic wrap pressed directly against the surface of the salad and refrigerate for up to a few hours. Enjoy on its own, in lettuce cups, or scooped onto tortilla chips.