Start by slicing your onion, pepper, and mushrooms.
Preheat your Blackstone griddle to medium-low heat.
Drizzle your avocado oil on the griddle surface and spread with a spatula to prevent sticking.
Add your onions, pepper, and mushrooms to the griddle, stir, and let them cook for a couple of minutes.
Then, using a squeeze bottle with water, squirt water over your veggies and cover with a dome lid to steam for 2 more minutes so they soften quicker.
While your onions, peppers, and mushrooms are cooking, add the shredded chicken to a bowl and combine with salsa.
Uncover your onions, peppers, and mushrooms, then add your seasoned shredded chicken and let it cook for 5 minutes or until the veggies are tender and start to caramelize.
Top with a cup of shredded cheddar cheese, then squirt water around the veggies and chicken, and cover with the dome cover to allow cheese to melt.
Remove the cheesy chicken and veggie mixture from the heat and set aside.
Divide the rest of the shredded cheese evenly among the tortilla shells, placing it on one side of the tortilla shell and then top with your seasoned chicken, cheese, and veggie mixture that was cooked on the griddle, and fold in half.
Add back to your Blackstone and cook each side for 1-2 minutes or until brown.
Serve with more salsa (if desired) and sour cream.