01 -
Heat the Blackstone grill to medium-high heat, around 400°F. Evenly spread vegetable oil across the grill top.
02 -
Scatter diced skirt steak and onions on the grill in a single layer. Season with onion powder, salt, and black pepper. Sauté, turning as needed, until steak is browned and fully cooked, approximately 4–8 minutes per side.
03 -
Push cooked steak and onion mixture to one side of the grill and reduce heat to medium.
04 -
Place tortillas on the cleared side of the grill. For each, layer half of the mozzarella and Monterey Jack cheeses, followed by the steak and onion mixture, then finish with remaining cheese.
05 -
Fold each tortilla in half to enclose the filing. Cook for 1–2 minutes until the underside is golden brown.
06 -
Carefully flip each quesadilla and cook for another 1–2 minutes until the opposite side is golden brown and cheese is fully melted.
07 -
Remove quesadillas from the grill, cut into wedges, and serve while hot.