Stephanie Izard's Blended Burger

Rhubarb Mostarda:

• 2 cups rhubarb, sliced
• 1 cup white wine vinegar
• 1/2 cup sugar 
• 1 tablespoon mustard seeds
• 1/2 tablespoon Dijon mustard

Burger Patties:

• 1 1/2 pounds 80/20 ground beef
• 1 pound shiitake mushrooms, stems removed
• 2 teaspoon kosher salt 

Asparagus Tapenade: 

• 2 cups asparagus, woody stems removed and greens sliced into 1/4 inch rounds
• 1/4 cup Niçoise olives, rough chopped
• 2 tablespoons fresh mint, rough chopped
• 1/2 tablespoon preserved lemon or lemon zest 

Brown Butter–Miso Aïoli: 

• 2 tablespoons white miso 
• 2 tablespoons brown butter
• 1/2 cup mayonnaise 
• 2 teaspoons lemon juice 
• 1/4 cup sour cream
• 1 cup arugula 
• 1 tablespoon extra virgin olive oil 
• 4 burger buns 

Make the rhubarb mostarda: bring the vinegar and sugar to a boil. Whisk the mixture to dissolve the sugar. While hot, pour 1 tablespoon of the mixture over the mustard seeds. Set aside the remaining vinegar and allow it to cool to room temperature. Pour the cooled vinegar over the rhubarb and allow it to sit for 2 hours. 

Strain and rough chop 1 cup of pickled rhubarb and mix it with the pickled mustard seeds and Dijon. The remaining pickled rhubarb can be stored in the refrigerator for up to a month. 

Make the burger patties: preheat the oven to 325 degrees.

Toss the shiitake mushrooms in cooking oil and season them with salt. Roast the shiitakes for 12 to 15 minutes, until tender. Allow the mushrooms to fully cool before processing in a food processor or finely mince them by hand. 

In a stand mixer with a paddle attachment or by hand, incorporate the meat, ground mushroom, and salt to a homogenous mixture. Form the mixture into 4 equal sized burger patties. Rest the patties in the refrigerator for at least 30 minutes.

Make the asparagus tapenade: heat a sauté pan over medium heat. Add a small splash of oil to the pan and sauté the asparagus until just tender, about 2 minutes. Transfer the asparagus to a bowl and allow them to cool. Once cooled, mix the asparagus with the Niçoise olives, fresh mint, and lemon. Refrigerate this mixture until ready to use.

Make the brown butter–miso aïoli: preheat the oven to 350 degrees. Spread the miso on a sheet tray and brown it in the oven for 4 minutes. Stir and cook the miso for another 3 minutes until it becomes a medium caramel color. Remove the tray from the oven and cool completely. 

Blend the toasted miso, brown butter, mayonnaise, and lemon juice until smooth. Transfer the mixture to a bowl and fold in the sour cream. This can be stored in the refrigerator for 3 days.

Build the burgers: sear or grill the burgers to your desired doneness. Toss the arugula in olive oil and a small pinch of salt and set aside. Spread the bottom bun with 2 tablespoons of brown butter miso aïoli and top with 1/2 cup of the asparagus tapenade. Top the asparagus with a cooked blended burger patty and dressed arugula. Spread the top bun with the rhubarb mostarda. Enjoy!