Bistro Burger with Blue Cheese, Caramelized Onions and Cornichon Aioli

Name: Bistro Burger with Blue Cheese, Caramelized Onions and Cornichon Aioli
Prep time: 25 min
Cook time: 10 min
Total time: 35 min
Yield: 4 servings
Cuisine: AMERICAN
Ingredients: 5 Tbs. (2 1/2 oz./75 g) salted butter, divided; 2 Tbs. olive oil; 1 yellow onion, thinly sliced; 1/4 cup (2 fl. oz./60 ml) water; Kosher salt; 6 garlic cloves, thinly sliced; 1 Tbs. fresh thyme leaves, minced; 2 Tbs. balsamic vinegar; 1 garlic clove; 1 cup (5 1/4 oz./150 g) cornichons, drained; 1 whole egg plus 2 egg yolks; Kosher salt; 1 cup (8 fl. oz./250 ml) neutral oil or mild olive oil; 1 lb. (500 g) ground beef, at room temperature; 5 Tbs. (5 oz./150 g) <b><a href="https://www.williams-sonoma.com/products/williams-sonoma-burger-starter-bourbon-caramelized-onion/">Williams Sonoma Bourbon Caramelized Onion Burger Starter</a></b>; Kosher salt and freshly ground pepper; Neutral oil as needed; 1/2 cup (2 1/2 oz./75 g) crumbled or thinly sliced French blue cheese; <br> 2 Tbs. salted butter; 4 brioche buns, split; Handful of arugula for serving

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Sweet caramelized onions combine with tangy cornichon aioli and our umami-rich burger starter in this French rendition of an American classic. Avoid pre-crumbled blue cheese, which tends to be chalkier with little flavor, and opt for a French cheese freshly cut from the wheel, if you can. Roquefort and Bleu d’Auvergne bring bolder flavors and provide a bright contrast to the burger. For a milder blue cheese, look for Saint Agur or Fourme d’Ambert.

Prep Time 25 minutes

Cook Time 10 minutes

Servings 4

Ingredients

For the caramelized onions:

5 Tbs. (2 1/2 oz./75 g) salted butter, divided
2 Tbs. olive oil
1 yellow onion, thinly sliced
1/4 cup (2 fl. oz./60 ml) water
Kosher salt
6 garlic cloves, thinly sliced
1 Tbs. fresh thyme leaves, minced
2 Tbs. balsamic vinegar

For the cornichon aioli:

1 garlic clove
1 cup (5 1/4 oz./150 g) cornichons, drained
1 whole egg plus 2 egg yolks
Kosher salt
1 cup (8 fl. oz./250 ml) neutral oil or mild olive oil

For the burgers:

1 lb. (500 g) ground beef, at room temperature
5 Tbs. (5 oz./150 g) Williams Sonoma Bourbon Caramelized Onion Burger Starter
Kosher salt and freshly ground pepper
Neutral oil as needed
1/2 cup (2 1/2 oz./75 g) crumbled or thinly sliced French blue cheese
2 Tbs. salted butter
4 brioche buns, split
Handful of arugula for serving

Directions

To make the caramelized onions, in a large skillet over medium heat, melt 3 Tbs. of the butter with the olive oil. Add the onion and cook, stirring occasionally, until the onion is thoroughly wilted, about 10 minutes. Add the water, cover and reduce the heat to medium-low. Cook, stirring occasionally, until most of the water evaporates, about 10 minutes. Add the remaining 2 Tbs. butter, a pinch of salt, garlic and thyme. Cook until the onions are melted down and caramelized, 15 to 20 minutes more. Add the balsamic, taste and adjust the seasoning with salt. Set aside.

To make the cornichon aioli, in a blender, combine the garlic, cornichons, egg, egg yolks and a generous pinch of salt and blend on high speed until smooth. With the machine running, slowly add a few drops of the oil and then follow with a slow, steady stream of oil. Continue to blend until thoroughly combined and emulsified, stopping the machine to scrape the sides of the blender as needed. Season to taste with salt. Set aside.

To make the burgers, prepare a medium-hot fire in a grill. Alternatively, follow the instructions below for using a stovetop grill pan, cast-iron fry pan or griddle.

In a bowl, mix the ground beef, burger starter, salt and pepper until combined. Divide the mixture into 4 equal portions, about 4 oz. (125 g) each. Gently use your hands to shape each portion into patties.

To cook on an outdoor grill: Brush the grill with oil. Place the patties on the grill and cook, turning once, until the patties form a crust, about 2 minutes per side for medium, or until done to your liking. During the last 2 minutes of cooking, top each burger with 1 Tbs. of the cheese. Cover with an upside-down baking sheet or a large heat-proof bowl and cook until the cheese is melted, about 45 seconds more.

To cook on a stovetop grill pan, cast-iron fry pan or griddle: Heat the pan over medium-high heat and lightly brush with oil; the pan is hot enough when a few drops of water flicked onto the surface skitter across it. Working in batches as needed, add the patties and cook, turning once, until the patties form a crust, about 2 minutes per side for medium, or until done to your liking. During the last 2 minutes of cooking, top each burger with 1 Tbs. of the cheese. Cover with an upside-down baking sheet or a large heat-proof bowl and cook until the cheese is melted, about 45 seconds more.

Transfer the burgers to a plate to cool slightly.

Wipe the grill or pan clean and brush with the butter. Place the buns, cut side down, on the grill or pan and toast until deep golden-brown underneath, about 1 minute. Transfer the buns, toasted side up, to a baking sheet.

To assemble, spread a layer of the aioli on the cut sides of the bottom and top buns. Top each bottom bun with a burger. Divide the remaining 1/4 cup (1 1/4 oz./40 g) blue cheese evenly among the burgers, then top with a pile of caramelized onions and arugula. Cover with the top buns and serve immediately. Serves 4.

Williams Sonoma Test Kitchen