When it comes to sandwiches, my go to has to be something with melted cheese. Paninis, grilled cheeses. and more are my absolute favorite! I went to Costco and found this huge package of thinly sliced beef, and I knew I had to make a delicious beef sandwich. Thinking back on some onions I had at home, I set out to make a cheesy beef sandwich with caramelized onions. It did not take long, and the result was INCREDIBLE and the best beef sandwich!
First, I buttered my brioche rolls with garlic butter. I melted 2 tbsp of butter and added garlic, parsley, and salt. Toast your buns until they are lightly golden brown.
For the thinly sliced beef, season with a mixture of 1-2 tsp each of salt, pepper, and garlic powder. Next, we will move onto the veggies. For my mixture, I used thinly sliced onions and portobello mushrooms. Get the cast iron hot and add 1 tsp of olive oil. Sauté. Add 2 tsp of sugar to help caramelize. Cook down for about 10 minutes until the onions and mushroom are tender and sweet.
Remove from the cast iron and add in your seasoned beef. This will not take super long to cook since it is thinly sliced. When the beef is done, it is time to assemble the sandwich! To your toasted garlic bread, add your cooked steak. Then top with the onion mixture. Next add your provolone cheese and add back into the toaster just to melt the cheese and crisp up your bread edges, This will take only a couple of minutes so keep an eye out. Lastly, remove from the toaster and sprinkle with parsley!
The Best and Cheesiest Beef and Onion Melt
- 1 lb Thinly Sliced Beef
- 1 Tsp Each: Salt, Pepper, Garlic Powder
- 1/2 Onion Thinly Sliced
- 1 Portobello Mushroom Thinly Sliced
- 1 Tsp Olive Oil
- 2 Tsp Sugar
- 4 Slices Provolone Cheese
- Parsley to Garnish
Garlic Butter Buns
- 2 Brioche Buns
- 2 Tbsp Butter
- 1 Tbsp Minced Garlic
- 1 Tsp Parsley
- 1/2 Tsp Salt
- Mix garlic butter together and spread on buns.
- Toast buns until golden brown. Set aside.
- Thinly slice your onions and mushrooms.
- In a hot cast iron, add 1 tsp of oil and sauté for about 10 minutes. Around the 5 minute mark, add 2 tsp of sugar.
- Removed cooked veggies.
- Season beef with salt, pepper, and garlic powder. Throw in cast iron and cook. It will not take too long.
- Assemble the sandwich with beef, then veggies, and top with cheese. Stick back into the toaster so the cheese melts and the edges crisp up!
- Sprinkle with parsley and enjoy!