Begin preheating your grill to 400°F. If using the stove, you can preheat a large cast-iron skillet over medium-high heat. Start by using a meat mallet to pound the steak to ¼-inch thickness, then cut off the ends to create a more even width with the meat. You can cook up the extra pieces!
4 pounds skirt steaks, trimmed and pounded to ¼-inch thickness
Next, drizzle the steaks with oil, and mix together the spice blend. Season generously on all sides.
2 tablespoons olive oil, 4 teaspoons kosher salt, 2 teaspoons coarse ground black pepper, 2 teaspoons onion powder, 2 teaspoons garlic powder, 2 teaspoons oregano, ½ teaspoon smoked paprika, ½ teaspoon red pepper flakes
Next, add a layer of cheese slices. We used 5 slices per steak. Follow that up with spinach and basil on top.
12 ounces provolone cheese, 1 cup fresh basil leaves, 2 cups fresh spinach
Roll the meat tightly, holding firm to ensure nothing falls out. The shape should be like a pinwheel, where you can see bits of cheese and green from the spinach and basil poking out.
Using kitchen twine or butcher's twine, tie the steak tightly in two places toward the middle of the roll, but giving about 1 to 1.5 inches of space between them. Using sharp kitchen shears, cut the excess string off above the tight knot.
Next, using a sharp knife, but the steak roughly in half, ensuring that each half has twine holding the steak in place.
Drizzle with more oil, then season with more salt and pepper on each side.
1 teaspoon coarse ground black pepper, 2 teaspoons kosher salt, 2 tablespoons olive oil
Add to the hot grill, then close the lid and let cook for roughly 8-9 minutes before flipping to get some really nice grill marks. Flip, then continue to cook until you're a few minutes under your desired temperature. We took ours off when an instant-read thermometer read 120ºF. All in, it took around 20-23 minutes to reach that temperature.
Allow the steak to rest for about 10 minutes, then drizzle with cowboy butter!