Rub the steak with chili powder and if it came from the fridge, let stand at room temperature for 10-15 minutes.
Cook the steak on grill preheated to high heat for 5 minutes, until char-marked with a deep golden crust.
Flip and cook for another 3-4 minutes for medium-rare, or until done to your liking.
Transfer to a cutting board and let rest for 10 minutes.
Slice the steak thinly across the grain.
Serve in tortillas with chopped tomato, onion, avocado and/or guacamole and/or salsa and/or sour cream. Top with cilantro and enjoy!
Alternate cooking instructions: Heat a drizzle of oil in a heavy skillet (cast iron is ideal) set over medium-high heat, and once the pan is hot, cook the steak for 5 minutes, until it develops a deep bottom crust. Flip and cook for another 5-6 minutes for medium-rare, or until done to your liking.