Combine all the ingredients for the marinade in a Ziploc bag (plastic bag). Shake it until everything is mixed and the steak is coated. Set aside at room temperature to marinate for 30 minutes.
While the steak is marinating, cut your onions and green onions.
Heat 1 tablespoon of oil in a cast iron pan over medium high heat. If you don’t have a cast iron, a non stick pan should work as well. Place the steak in the pan and let it cook until it gets a good sear (3-5 minutes).
Flip the steak over. Add the butter. Spoon the melted butter over the steak. This will help cook the steak further and give it a nice sear. Once the steak has a nice sear on the second side, make sure to sear all the other sides too. The steak should be a medium rare to medium at this point. If you want to cook the steak more, put the steak in the oven for a few minutes.
Once the steak is cooked to your preferred doneness, place it on a cooling rack to rest. This ensures that all the juices don’t flow out when you cut into it.
Next, cook your onion and green onion. Throw them into the cast iron and cook until the onions are translucent. Set aside.
Next add the tomatoes and cook for a few minutes. Set aside.
Lastly, fry the egg. Set aside.
Drain excess oil from the pan and place the steak, onion, green onion, tomatoes, and egg back into the cast iron. Add the cucumbers, pate, and baguette.
Serve the bo ne in the cast iron!