FIRST In a large bowl, stir together garlic, lime juice, jalapeño, cilantro, oil, vinegar, salt, and pepper. Add steak, turning to coat. Cover and refrigerate for at least 2 hours or overnight.
LAST Heat a cast-iron grill pan over medium-high heat. Add steak (discarding marinade); grill for 7 minutes. Turn, and cook until desired degree of doneness, 7 to 12 minutes more. Let rest for 10 minutes; slice, and serve. Garnish with jalapeño rings, if desired.
Recipe by Southern Cast Iron at https://southerncastiron.com/grilled-carne-asada/