In a large bowl whisk together all the MARINADE ingredients.
Add the steaks and marinade, either in a large ziplock bag or in the bowl, tossing the steaks a few times to coat. If using a ziplock bag, press the excess air out and seal the bag. Chill for at least 30 minutes to a few hours.
Preheat the grill to medium-high and lightly rub it with some olive oil. You can also use a grilled pan, over medium-high heat.
Use tongs to transfer steaks onto the preheated grill. Cook until desired doneness is reached, use a meat thermometer to check the temperature: for RARE less than 130 degrees, for MEDIUM-RARE 130 degrees, for MEDIUM 135 degrees, for MEDIUM-WELL 150 degrees and for WELL-DONE 160 degrees.
Allow steaks to rest for 5 minutes before serving. Garnish with fresh green onions and butter if desired.