Step 1

In a small bowl, whisk together chili powder, cumin, paprika, sugar, garlic powder, onion powder, cayenne pepper, and salt to taste (I like 1 teaspoon).

Step 2

To a large zipper-top plastic bag, add steak, cilantro, lime juice, and fajita seasoning. Mash until steak is evenly coated. Marinate at least 30 minutes (room temperature) or up to 1 hour (refrigerated).

Step 3

In a large skillet over medium-high heat, heat oil until shimmering. Add steak and cook, without moving, until crispy and browned on one side, about 3 to 5 minutes. Flip and cook until browned on the second side, about 3 to 5 minutes longer.

Step 4

Using tongs, stand each piece on a cut side and cook, turning as necessary, until all cut sides are browned and until meat registers 120 to 125 degrees (for medium rare) or 130 to 135 degrees (for medium), 3 to 8 minutes.

Step 5

Transfer steak to a cutting board and rest for 5 minutes before cutting into strips (do not discard fat in skillet). Slice steak pieces thin against grain.

Step 6

Meanwhile, to the skillet with the fat over medium-high heat, add bell peppers and onions and cook until tender, about 5 minutes. Push peppers and onions to one side and add sliced steak back to skillet for serving. Serve with tortillas and your favorite toppings.