Steak and Gruyere Sandwich Recipe (with Video)

Preparing the Onions
1. Heat 1 tablespoon of olive oil and 1 tablespoon of butter in a large skillet over medium-low heat.
2. Add the thinly sliced red onions to the skillet and cook slowly, stirring occasionally, until they become soft and golden brown.
3. Season with a pinch of salt and set aside.
Cooking the Steak
1. In a separate skillet, heat the remaining 1 tablespoon of olive oil over medium-high heat.
2. Add the shaved rib eye steak to the skillet and season with salt and pepper to taste.
3. Cook the steak for about 2-3 minutes per side or until it's cooked to your desired level of doneness.
4. Turn off heat and add the Gruyere to the pan with the steak, mixing well to combine.
Assembling the Sandwich
1. Slice the French baguettes or sandwich rolls in half lengthwise and spread the truffle mayonnaise generously on both sides of the baguettes or rolls.
2. On the bottom half of each baguette or roll, evenly distribute the arugula or spinach if using.
3. Place the cooked rib eye steak on top, then evenly distribute the caramelized onions on top of the steak.
4. Cut each sandwich in half and serve warm.
5. Enjoy!