Almost Award-Winning French Bistro Smashburger

Dinner Club Diaries
by Dinner Club Diaries
4 Burgers
1 hr 5 min

Last July, I entered The Mushroom Council's contest to create a "blended burger" - a burger comprised of at least 25% mushrooms in the patty. So I got to work creating a burger with all my favorite French flavors: a beef and mushroom patty flavored with sherry wine, shallots, garlic and thyme. Melty Gruyère cheese. Onions caramelized with brown sugar, balsamic vinegar and Worchestershire sauce. Garlicky aioli with punchy cornichons. A sweet brioche bun. But the best part? Make it a smashburger! 2 thin, crispy patties only take minutes to cook, especially on a Baking Steel!​

Out of almost 500 entries, I was selected as one of three finalists! Each contestant had a video chat with Chris Morocco, Test Kitchen Director at Bon Appétit, who made each of the three burgers based on our recipes. He tasted them and selected a winner! Talking to Chris and watching him make and eat MY burger was such an unbelievable experience! And although I did not win the contest, I am forever grateful for this unique experience, and for this delicious burger! You can do this!

Do you want to see the video and find out who the winner was??? Video is about 10 minutes and I'm the last contestant!

Almost Award-Winning French Bistro Smashburger

Look at that cheese and balsamic onions!

Chris Morocco of Bon Appetit test kitchen making and tasting my burger!

He liked it!!!

Almost Award-Winning French Bistro Smashburger
Recipe details
  • 4  Burgers
  • Prep time: 1 Hours Cook time: 5 Minutes Total time: 1 hr 5 min
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For the Balsamic Onions
  • 1 very large Vidalia onion, thinly sliced
  • 1 T brown sugar
  • 2 T balsamic vinegar
  • 2 T Worcestershire sauce
For the Blended Burger Patties
  • 2 T olive oil
  • 2 T butter
  • 2 T finely minced shallots
  • 1 clove minced garlic
  • 1 sprig fresh thyme
  • 12 oz baby Bella (crimini) mushrooms, finely chopped
  • 2 T sherry wine
  • 1 lb ground chuck
Cornichon Aioli
  • 2 large egg yolks
  • 1 t dijon mustard
  • 1 finely grated garlic clove
  • Pinch of salt
  • 3/4 c Extra virgin olive oil
  • 2 T lemon juice
  • 2 T cornichons (like Maille)
Make the Burgers
  • 8, 3 oz Blended Burger Patties
  • Cornichon Aioli
  • Shredded Gruyère cheese
  • Balsamic Onions
  • 4 Toasted Brioche Buns (like St. Pierre Bakery)
For the Balsamic Onions
Melt 1 T butter and 1 T olive oil in a sauté pan.
Thinly slice 1 very large Vidalia onion and cook over medium-low heat covered about 20 min, caramelizing the onions. Add in brown sugar, then balsamic vinegar and Worcestershire sauce, and cook uncovered until liquid reduces away, creating jammy onions, about another 40 minutes.
Season with salt and pepper. 
For the Blended Burger Patties
While the onions are caramelizing, start on the mushrooms. Melt 1 T butter and 1 T olive oil in a sauté pan.
Sauté the shallots and garlic with thyme over medium-low heat so as not to burn them.
Add in chopped mushrooms, along with 1 T butter and 1 T olive oil, and sauté until fully cooked and all liquid has evaporated.
Add sherry wine to pan and again cook until liquid is gone. Season with salt and pepper, remove thyme sprig, and allow to cool completely. You should end up with about 8 oz of cooked mushrooms.
Combine with 16 oz ground chuck and form into 3 oz balls. Each smashburger will be comprised of two 3 oz patties (2/3 meat and 1/3 mushrooms). I like to prep the patties in advance, smashing each one between 2 pieces of wax paper with a frying pan, and storing in the fridge until ready to cook. Makes 8 patties total for 4 smashburgers.
For the Cornichon Aioli
Combine 1 recipe homemade aioli, plus 2 T finely minced cornichons (like Maille).
(I recommend Bon Appétit’s Grand Aioli recipe
Alternatively, use 1/2 c high quality store-bought mayo, 1 t dijon mustard, 2 T lemon juice, 1 clove finely minced garlic, pinch of salt, and 2 T finely minced cornichons.
Make the Burgers
Grill each burger patty on an oiled, flat top griddle - Baking Steel on outdoor grill highly recommended! - about 3 minutes per side, or until edges are charred and crispy.  (Alternately, use a cast iron pan.)
Salt the uncooked side of the patty, then flip the patties over and salt that side.
Top with Gruyère cheese and cover with lid or grill cover briefly to allow cheese to melt.
Layer 2 patties on top of each other, and transfer to bottom half of toasted Brioche bun. Top patties with Balsamic Onions. Add a good schmear of Cornichon Aioli to the top half of the toasted Brioche bun and voilà! Blended French Bistro Smashburgers!!! Serve with pommes frites, of course!
  • The trick to the best caramelized onions??? TIME. After the initial 1 hour stated in the recipe, continue to cook over low heat for as long as you have... even up until the time you serve the burgers!
Dinner Club Diaries
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  • Tricia Lynn Mitlehner Tricia Lynn Mitlehner on Jun 13, 2021

    This burger, minus the mushrooms, would be a winner in my book! I will adapt the recipe to leave out the mushrooms... Looks delicious though!!! Thanx for sharing! Still a winner in my book!

  • Marcylynn Marcylynn on Jun 14, 2021

    I love the above burger idea but what do you have for someone who can only eat beef allergies to three types of mushrooms onions garlic and all peppers plus non diary and gluten free. That's my challenge in eating anything also no citrus . No oats and like 6 more pages of what I can't have. Help hunger in Seattle.

    • Dinner Club Diaries Dinner Club Diaries on Jun 14, 2021

      So sorry to hear this! Must be tough to manage. Can you have powdered forms of onions and garlic?