Place your flank steak on a cutting board, flatter side down.
Using an extremely sharp boning knife, butterfly the flank steak.
It should be evenly-thin (about 1/4 an inch thick) all over. If necessary, pound with a mallet to even it out.
Peel the green chiles under a stream of running water.
Place the peeled chiles on a paper towel and use scissors to remove the stem tops.
Remove the seeds from the chiles and cut down one side to open them flatly.
On the cutting board, arrange the butterflied flank steak.
Atop the steak, add an even layer of green chiles.
Put an even layer of sliced pepper jack cheese on top of the chiles.
Working against the grain, roll the steak tightly into an even roll.
Using a combination of skewers and kitchen twine, secure the roll tightly.
With a sharp knife, cut the roll into even pinwheels (ours made 4 about 1 1/2 inches thick).
We found that a piece of kitchen twine between two skewers did the best to keep the pinwheels tight.
Preheat your Traeger Flatrock Griddle to medium-high heat.
Spray a thin coating of vegetable cooking spray on the hot griddle.
Insert a Meater thermometer probe in one steak and green chile pinwheel and set the temperature to 130*.
Place the pinwheels on the griddle and cook for about 10 minutes.
Move the pinwheels to a cooler part of the grill as necessary to allow them to continue to cook without burning.
Flip the pinwheels and continue cooking until the internal temperature reaches 130*.
You can also sear them on a hot part of the grill for about 3 minutes per side, and then transfer to a medium part of the grill and continue cooking for 10-15 minutes, flipping frequently, until they reach 130*.
Transfer the cooked green chile pinwheels to a cutting board and allow to rest for a few minutes.
Cut the twine off the pinwheels.
Using a sharp knife, slice between the skewers.
Serve the steak and green chile pinwheels with a simple side like sweet potato fries and enjoy.