These mouthwatering Open Faced Mushroom And Onion Steakburgers are an elegant way to serve a burger for a special meal or as an appetizer. Fresh hoagie rolls are slathered with garlic butter then topped with seasoned ground sirloin and baked until the beef is cooked through. Top with sauteed mushrooms and caramelized onions they’re ready to smother with cheese. Place under the broiler until the cheese is gooey and golden. Cut into pieces and serve with dippers as an appetizer, game day treat or a small bites meal.
How often have you heard the word elegant used when talking about a burger? These steakburgers are just that when served with basil pesto or sundried tomatoes on the side at a casual soiree. I personally enjoy serving them both as an appetizer as well as a small bites meal.It’s sort of a grown-up way to eat an everyday cheeseburger and the buttered, garlicky, cheesy baguette makes it over the top gourmet good! In those moments I don’t have time to grill, or the weather won’t permit, these delectable open faced burgers curb the burger craving spot.
You may also like: Chicken Burgers with Feta and Sundried Tomatoes, Teriyaki Burgers with Grilled Pineapple and Smash Burgers.
Disclosure ~ If a purchase is made using one of the affiliate links on this website we may earn a small commission at no additional cost to you. Thank you!
Helpful Kitchen Items:
Open Faced Mushroom And Onion Steakburgers
Servings 16 Pieces
- 1  inch soft french baguette
- butter/light butter
- garlic salt
- 10-12 thick slices muenster/sharp cheddar/swiss cheese [your preference]
- For the steak burgers:
- 2 lb extra-lean ground sirloin
- 1 large egg
- 1 1/2 tsp steak seasoning [like Kansas City]
- 1 Tbsp steak sauce
- For the mushrooms & onions:
- 8 oz sliced button/baby portabella/cremini mushrooms [your preference]
- 1 large sweet onion thinly sliced
- 2 tsp fresh thyme
- 1 Tbsp balsamic vinegar
- a couple pinches of sugar
- salt & black pepper to taste
- olive oil
- Preheat the oven to 400°F and move the oven rack to the upper 1/3 of the oven. By moving the oven rack closer to the top element the meat will cook evenly without overcooking the baguette. Line a large baking sheet with parchment.
- Slice the baguette through the middle, then cut each portion in half again making 4 pieces. Arrange side by side on the baking sheet. Butter each piece and sprinkle lightly with garlic salt. Cut the cheese slices in half.
- Arrange half of the cheese slices over the buttered baguette reserving the other half for the top.
- In a skillet over medium-high heat, cook the mushrooms and onions in a couple of drizzles of olive oil until golden.
- Add the fresh thyme and season with salt and black pepper to your taste. This will take about 10-12 minutes.
- Add a tablespoon of balsamic vinegar and a couple pinches of sugar to sweeten the onions, then cook for an additional 2 minutes. Remove from the heat and set aside to cool slightly.
- Mix together all of the steak burger ingredients. Divide evenly between the baguettes, spreading to the edges. The meat will be thin.
- Place into the oven and bake for 20-22 minutes depending on the thickness of the meat. Remove from the oven, place the sauteed mushrooms and onions on top, then cover with the remaining cheese.
- Set the oven on broil, then return to the oven until the cheese melts.
- Cut each steakburger into 4 equal pieces and serve with an assortment of flavored mayonnaise, pesto or spreads.