Toss steak with half the fajita seasoning. Heat 1 tablespoon oil in a large skillet over medium-high.

Cook peppers and onion 6–8 minutes; transfer to a plate.

Add remaining oil; cook steak in batches 3–5 minutes until 145°F. Rest 3 minutes.

Return vegetables; add broth and remaining seasoning. Simmer 2 minutes; serve in tortillas.