Bring a small amount of water to a boil in a pan with a steaming rack, ensuring the water doesn't touch the rack.

Combine salt, pepper, chili pepper, onion powder, and garlic powder in a small bowl to create the spice mix.

If using chicken breast, cut it into 1-inch thick strips for even cooking.

Sprinkle half of the spice mixture evenly onto the chicken strips.

Place the spiced chicken in a single layer on the steaming rack.

Cover the pan and steam the chicken for 6-7 minutes, or until it's fully cooked and white throughout.

If your steaming rack is small, steam the chicken in batches to avoid overcrowding.

Shred the cooked chicken using two forks.

In a bowl, mix the remaining spice mix with 2 tablespoons of water from the pan and 4 tablespoons of lime juice to create a sauce.

Pour the lime juice and spice sauce over the shredded chicken and mix well to combine.

Peel and remove the seed from the avocado, then dice the flesh.

Dice the tomatoes into small pieces.

In a small bowl, combine the diced avocado, diced tomatoes, and the remaining 1 tablespoon of lime juice.

Preheat the oven on low broil with the rack positioned in the upper half of the oven, but not directly under the heat source.

Line a standard size cookie sheet with a layer of tortilla chips.

Layer the ingredients as follows: half of the shredded Monterey Jack cheese, the seasoned chicken, the avocado and tomato mixture, chopped scallions, and then top with the remaining cheese.

Broil the nachos for approximately 3 minutes, or until the cheese is melted and bubbly.

Monitor the nachos closely during broiling as they can burn quickly.