Prepare charcoal grill for two-zone heat. Remove steaks from marinade (do not pat dry), and place over hotter part of grill. Cook, uncovered, until well browned on first side, 3 to 4 minutes. Flip steaks and cook until well browned on second side, 3 to 4 minutes. Transfer steaks to cooler part of grill, with wider end of each steak facing hotter part of grill. Cover and cook until meat registers 145 degrees, 3 to 8 minutes longer. (If using a gas grill, brown both sides over direct heat as above, then move to a zone without flame beneath to finish.) Transfer steaks to a carving board; let rest for 5 minutes.
Microwave reserved sauce until warm, 15 to 30 seconds; stir in cilantro. Slice steaks against grain into 1/2-inch-thick slices. Drizzle with half of sauce; sprinkle with sea salt, if using; and serve, passing remaining sauce separately.
Nutrition information per each of 6 servings:
Calories350Fat21 gSodium410 mgSaturated fat4 g
Carbohydrates4 gTotal sugars3 g
Protein34 gCholesterol95 mgDietary fiber0 g