For marinade, in a blender combine green onions, lime juice, ginger, Scotch bonnet pepper (if desired), oil, garlic, and jerk seasoning; cover and blend until smooth. Score both sides of steak in a diamond pattern by making shallow cuts at 1-inch intervals. If desired, season steak with kosher salt and pepper. Place steak in a glass dish; spread marinade over the steak. Cover dish with plastic wrap and marinate in the refrigerator for 4 to 24 hours. Drain steak, discarding marinade.
For a charcoal grill, place steak on the rack of an uncovered grill directly over medium coals. Grill for 17 to 21 minutes or until medium doneness (160°F), turning once halfway through grilling. (For a gas grill, preheat grill. Reduce heat to medium. Place steak on grill rack over heat. Cover and grill as above.)
To serve, thinly slice meat diagonally across the grain.
*Note: Because hot chile peppers contain oils that can burn your skin and eyes, wear rubber or plastic gloves when working with them. If your bare hands do touch the chile peppers, wash your hands well with soap and water.