Bolognese Burger

• 1 small carrot, roughly chopped
• 1 small celery stalk, roughly chopped
• 1/4 yellow onion, roughly chopped
• 2 teaspoons olive oil
• 1/2 cup dry red wine (preferably one you wouldn't hesitate to drink)
• 2 cups strained tomatoes (such as Pomi)
• 1 teaspoon salt, plus more to taste for the burger patties
• 1 tablespoon dark brown sugar, packed
• 1/2 cup mayonnaise
• 1/4 cup grated parmesan, packed
• 2 small garlic cloves, peeled and smashed
• 1 1/4 pounds ground beef, at least 15% fat content
• 12 ounces ground pork
• 4 ounces pancetta, finely diced
• 6 ounces young fontina cheese, grated
• 6 lightly toasted burger buns, either regular white or brioche
• 1 1/2 cups fresh arugula, packed
• 1/2 red onion, sliced into thin rings

1. To make the aioli: place mayonnaise, parmesan, and garlic in a food processor. Blend until mostly smooth and only small flecks of parmesan remain. Transfer to a small bowl, cover, and refrigerate until use.
2. To make the tomato sauce: place the chopped carrot, celery, and onion in a food processor, pulse until the mixture is minced. In a medium saucepan, heat up olive oil on medium high. Add vegetable mixture and cook until most of the liquid has been absorbed, 6 to 8 minutes. Add red wine and cook for 1 minute. Add strained tomatoes, salt, and sugar. Turn down the heat to medium low and simmer for 35 minutes, stirring every few minutes to prevent scorching, until the sauce has reduced by 1/3 to 1/2. Transfer about 1/3 cup of sauce to a small bowl and reserve for burger assembly, set the rest aside by your stove for brushing burger patties with while they are cooking.
3. To make the burgers: combine ground beef, ground pork, and pancetta in a large bowl and mix well with either your hands or a spoon. Form the mixture into six 6 oz patties. Place an indent in the middle of each patty so it doesn't puff up in the middle while cooking.
4. Heat up a cast iron griddle or skillet on medium high (or have your outdoor grill ready). Have the tomato sauce and a brush close at hand. Liberally salt one side of each patty and place, salt side down, on the griddle. Salt the other exposed side, cook for 2 minutes then gently flip. Generously brush the top of each patty with tomato sauce, cook for another 2 minutes and flip again. Generously brush the other side with tomato sauce, cook for 2 minutes then flip one final time so the tomato sauce on both sides gets a chance to come into contact with the pan and caramelize. Add 1 oz of grated fontina on top of each patty and cook for 1 to 2 more minutes (covered, if you want the cheese to get really melty), for a total cooking time of 7 to 8 minutes for medium burgers. Adjust cooking times as necessary for your desired doneness.
5. To assemble: place a spoonful of the reserved tomato sauce on the bottom bun. Place burger patty on top. Add a heaping handful of arugula and a few rings of sliced red onion. Smear some aioli on the top bun and finish off the burger by placing it on top.

carrot, celery stalk, yellow onion, olive oil, red wine, tomatoes, salt, brown sugar, mayonnaise, parmesan, garlic, ground beef, ground pork, pancetta, fontina cheese, burger buns, fresh arugula, red onion

Taken from food52.com/recipes/29301-bolognese-burger (may not work)