In a small bowl, mix together olive oil, lime juice, chili powder, cumin, garlic powder, salt, and pepper.
Place the flank steak in a shallow dish and pour the marinade over it. Ensure the steak is well coated, and let it marinate for at least 10 minutes.
Heat a large skillet over medium-high heat. Cook the steak slices in the hot skillet until browned and cooked to desired doneness, about 2-3 minutes per side.
Warm the corn tortillas either in the microwave or on a second skillet over medium heat.
Assemble the tacos by filling each tortilla with steak slices and topping with cilantro, avocado, onion, and pico de gallo.
Notes
Feel free to add cheese or your favorite hot sauce for extra flavor.