In a large resealable plastic bag, combine steaks and remaining ingredients. Seal, and refrigerate for at least 1 hour before grilling.
Remove steaks from refrigerator approximately 30 minutes before grilling. Preheat grill to 450°. Brush grill with oil. Place steaks on grill; cover, and cook approximately 3 to 4 minutes per side or until meat has reached desired degree of doneness.
Remove steaks from grill. Let rest for at least 10 minutes before slicing thinly.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/grilled-rosemary-garlic-skirt-steaks/