Step 1

Combine everything except the flat iron steak (the olive oil, soy sauce, red wine vinegar, garlic, rosemary, and black pepper) in a gallon-sized ziptop plastic bag. Shake or swish the bag to combine.

Step 2

Place the flat iron steak in the bag of marinade and squeeze out as much air as possible before closing the bag tightly. Squeezing out the air ensures that the beef is sufficiently coated in the marinade.

Step 3

Marinate the meat ideally for 4 hours*** and up to 1 day ahead.

Step 4

Preheat a gas grill on high for at least 10 minutes, heating all burners.

Step 5

Remove the meat from the marinade, then place in the center of the grill. Close the lid, and cook for 90 seconds.

Step 6

Check that there are grill marks underneath, then pivot the meat 90 degrees (I do this to an untouched part of the grill grates so I get the best possible sear on the beef), and again close the lid and cook for 90 more seconds.

Step 7

Flip the steaks over. Close the lid, and cook for 90 seconds.

Step 8

Pivot the meat 90 degrees to get grill marks going the other way again, close the lid, and cook for another 90 seconds.

Step 9

Because this cut of beef is so thin, there's a good chance it's already done. Check internal temperature with a thermometer. I aim for between 125F and 130F, but you may cook to your desired level of doneness, repeating these 90 second intervals with the lid closed. Just remember that the meat will rise another 5 degrees or so while resting because of carryover cooking.

Step 10

Remove the steaks to a wire rack or tray and let rest for at least 5 minutes before slicing and serving. Enjoy!