Thinly slice the flank steak against the grain into bite-sized strips.
In a small bowl, combine the sea salt, black pepper, garlic powder, and smoked paprika, then toss with the steak strips to coat.
Heat half of the olive oil in a cast-iron skillet over medium-high heat and sear the steak until browned and cooked to your preference, about 3 minutes; remove and set aside.
Add the remaining oil to the same skillet and sauté the sliced bell peppers and onions until they are tender and slightly charred.
Wipe the skillet clean and place the tortilla in the pan over medium heat.
Sprinkle half of the pepper jack cheese over one half of the tortilla.
Layer the seared steak and sautéed vegetables over the cheese, then top with the remaining cheese.
Fold the tortilla in half and press down gently with a spatula.
Cook for 2-3 minutes per side until the tortilla is golden brown and the cheese is completely melted.
Remove from heat, let rest for one minute, then slice into wedges and serve.