In a mixing bowl, whisk together olive oil, minced chipotle peppers, garlic, lime juice, cumin, salt, and black pepper.

Place the flank steak in a large zip-top bag and pour the marinade over it.

Seal the bag and massage the marinade into the steak for even flavor distribution.

Let the steak marinate in the refrigerator for at least 15 minutes, or up to 2 hours.

Preheat your grill pan or outdoor grill over medium-high heat.

Remove the steak from the marinade and discard the marinade.

Place the steak on the grill and cook for about 5 minutes on each side for medium-rare.

Use a meat thermometer to check for doneness; it should read 130°F for medium-rare.

Once cooked, remove the steak from the grill and let it rest for 5 minutes.

Slice the steak against the grain into thin strips and serve.