Marinate the flank steak with chili powder, cumin, salt, and pepper for at least 30 minutes.
Preheat your grill or skillet to medium-high heat.
Cook the marinated steak for about 5-7 minutes on each side until desired doneness.
Remove the steak from heat and let it rest for 5 minutes before slicing thinly.
Warm the corn tortillas on the grill for about 30 seconds on each side.
Assemble the tacos by placing sliced steak on each tortilla.
Add chopped onions and cilantro generously on top of the meat.
Drizzle with salsa to taste.
Serve with lime wedges on the side for squeezing over the tacos.
Enjoy your delicious street tacos!