In a medium bowl, whisk together ¼ cup olive oil and ¼ cup fresh lime juice until well combined. Add 2 tablespoons of chili powder, 1 teaspoon of cumin, 1 teaspoon of garlic powder, and a generous pinch of salt and black pepper. Mix until a smooth paste forms.

Place the 1.5 pounds of flank steak in a shallow dish or a zip-top bag, and pour the marinade over the meat. Massage the marinade into the steak and seal. Marinate in the refrigerator for at least 30 minutes, or overnight for maximum flavor.

Preheat your grill or cast-iron skillet over medium-high heat for about 5 minutes.

Carefully place the marinated flank steak on the hot grill or skillet. Cook for approximately 4 to 5 minutes on one side, then flip and cook for an additional 4 to 5 minutes for medium-rare.

Remove the steak from heat and let it rest for 5 minutes before slicing.

Slice the steak thinly against the grain and serve with your preferred sides.