Slice the top sirloin steak into thin strips and season evenly with sea salt, black pepper, garlic powder, and smoked paprika.
Heat the avocado oil in a large skillet over medium-high heat until shimmering.
Add the steak strips to the skillet and sear for 2 to 3 minutes until browned and cooked through, then remove the steak and set aside.
In the same skillet, add the sliced onions and bell peppers, sautéing for 4 to 5 minutes until tender and slightly charred.
Wipe the skillet clean and return it to medium heat, then place the tortilla in the pan.
Sprinkle half of the shredded cheddar cheese over one half of the tortilla.
Layer the seared steak and sautéed vegetables over the cheese, then top with the remaining cheddar.
Fold the tortilla in half and cook for 2 minutes per side until the exterior is golden brown and the cheese is fully melted.
Remove from the pan, let rest for one minute, and slice into wedges before serving.