Combine onion, chiles, and cilantro into a bowl. Sprinkle with salt and pepper. Lightly press with potato masher to release flavors and muddle.

Add avocados and lightly mash again, leaving chunky.

Add tomato, more salt and pepper, picante, and mayo. Stir together. Add lime juice to taste.

To keep avocados from turning brown, cover with plastic wrap directly touching the guacamole - press down so no air reaches the avocados. Refrigerate any unused portions.