01 -
Preheat Blackstone griddle to medium-high heat (about 400°F). Evenly coat the surface with vegetable oil.
02 -
Scatter diced steak and onions across the griddle in a single layer. Season evenly with onion powder, salt, and black pepper. Sauté 4-8 minutes per side until steak is deeply browned and onions are softened.
03 -
Move the steak and onions to one side of the griddle. Adjust heat to medium.
04 -
Lay flour tortillas flat on the cleared portion of the griddle. Sprinkle each with a generous layer of mozzarella and Monterey Jack cheese, then top with cooked steak and onions. Add remaining cheese over the filling.
05 -
Gently fold each tortilla in half to form a half-moon. Cook 1-2 minutes on one side until the exterior is crisp and golden brown.
06 -
Carefully flip each quesadilla using a large spatula. Cook an additional 1-2 minutes or until both sides are golden with cheese fully melted.
07 -
Transfer quesadillas to a cutting board. Slice into wedges and serve immediately for maximum crispness.