Place 1 tablespoon oil, vinegar, garlic, salt, and pepper into a gallon sized ziplock baggie, mix until combined, then add in steak. Be sure to fully coat the steak in the marinade.

Let sit at room temperature for 30 minutes or (preferably) place in the fridge for 8 hours to marinate.

Heat remaining 1 tablespoon oil in a sauté pan for 3 minutes over medium-high heat.

Sear steak for 3-5 minutes per side or until the internal temperature reaches 135 degrees F or until the steak is cooked your liking*.

Let rest for 10 minutes before slicing.

While the steak is resting, melt butter in a non-stick skillet over medium heat.

Once melted, add in yellow onion and season with salt and pepper, to taste.

Cook, stirring regularly, until the onions are cooked to your liking, about 5-10 minutes.

Preheat broiler on the oven and line a baking sheet with a silicone baking mat.

Place the halved rolls onto the prepared baking sheet, then spread each with the herb butter.

Top 4 halves with the steak, onions, then cheese.

Keep the sandwiches open and broil for about 2 minutes or until cheese is bubbly and melted.

Top with arugula, if desired, and enjoy!

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