Slice steak against the grain into 1⁄3"-thick strips; place in a bowl. Add orange juice, 1 tbsp oil, and seasoning. Toss to coat. Set aside to marinate.
Dice avocado, tomato, and onion.
In Sauté Pan, heat remaining 1 tbsp oil. Add steak in a single layer, if possible. Cook in two batches, if required. Cook 1 min, flip, then cook additional 1 min–1 min 30 sec, or until steak is done to your liking.
Add steak, avocado, tomato, and onion to tortillas and serve with toppings, if desired.
Per serving (2 tacos): Calories 430, Fat 20 g (Saturated 5 g, Trans 0 g), Cholesterol 45 mg, Sodium 600 mg, Carbohydrate 34 g (Fiber 7 g, Sugars 3 g), Protein 30 g.