Rub steaks with oil and season lightly with kosher salt and black pepper. Cover; chill 2 to 24 hours. Let stand at room temperature 30 minutes before grilling.
Heat grill to medium-high, arranging coals on one half of grill. Season steaks again with kosher salt and black pepper. Grill on rack of uncovered grill directly over coals about 10 minutes or until well caramelized. When flare-ups happen, turn and move steaks to a new area of grill to avoid flames. Move steaks to side of grill without coals. Grill, covered, 12 to 18 minutes more for medium doneness (145 degrees F), turning and basting with Black Gold every 5 to 8 minutes.
Transfer the steak to a platter or cutting board and let rest for 8 minutes before slicing. Brush with a fresh teaspoonful of Black Gold and sprinkle with sea salt.
Place fat in a small saucepan over low heat. Add herbs, green onions, garlic, and lemon half. Cook just until herbs begin to wilt (but not sizzle) and mixture is 140 degrees to 150 degrees F. Remove from heat and let stand 15 minutes so flavors can marry. When using to baste, keep in warm spot on grill. Strain before storing; refrigerate up to a week. Add more herbs when rewarmed.