Fall Cheeseburgers with Mushrooms, Red Onions, and Truffled Mayo

Truffled Mayo (Recipe follows.)

1 1/3 pounds ground beef, pound ground beef, preferably 80% or 85 % lean
Kosher salt
Olive oil
8 oz baby bella or brown mushrooms, sliced through stems
1 medium red onion, peeled and cut crosswise into 1/2-inch thick rings
1 tbsp balsamic vinegar
Freshly ground black pepper
4- to 5-oz or larger piece aged provolone, Italian Fontina, or other good melting cheese, thinly sliced
4 brioche or other good quality hamburger buns

1.Prepare the Truflled Mayo and set aside. (If not using immediately, cover and refrigerate.)

2.Shape the ground beef into 4 equal patties about 4 inches in diameter and 1/2- inch thick. Cover with plastic wrap and refrigerate until needed. (Burgers can be prepared a day ahead; bring to room temperature 30 minutes before cooking.)

3.Heat 1 tablespoon olive oil in a large, heavy skillet over medium heat. When hot, add the sliced mushrooms, and cook, stirring until lightly browned, about 5 to 6 minutes. Add more oil if needed. When done, season with 1/4 teaspoon salt and remove to a plate.

4.To the same skillet (still set on medium heat) add 1 tablespoon plus 1 teaspoon olive oil. When hot, add onion rings, and sauté, stirring, until softened, about 4 to 5 minutes. Then stir in 1 tablespoon balsamic vinegar and season onions with 1/4 teaspoon salt. Remove to a plate. (Both onions and mushrooms can be prepared 2 hours ahead. Cover loosely with foil and reheat before cooking burgers.)

5.Prepare grill for a hot fire (high temperature). Combine 1 teaspoon kosher salt and 1/2 teaspoon black pepper and season burgers on both sides with this mixture. Brush cut sides of buns lightly with olive oil, and place on grill for 30 seconds or more, just to grill slightly. Remove buns.

6.Grill burgers 3 minutes and then turn. Top each burger with enough cheese slices to cover. (You may have some cheese left over.) Continue grilling until meat is just pink in the center, about 2 minutes or longer or until internal temperature in center of patties is 145 degrees. For well done, cook to 160 degrees F. Watch carefully as cooking time can vary depending on the intensity of the heat and the type of grill used. (You can also use a stove top grill pan to cook the burgers.)

7.Remove burgers from the grill. Spread cut sides of buns with Truffled Mayo. Spoon mushrooms on bottoms of buns, top with burgers, and then with onion rings Cover with tops of buns. Serve immediately. Serves 4.

Truffled Mayo 
1/4 cup good quality prepared mayonnaise such as Hellman’s
1 1/2 teaspoons white truffle oil (See cooking tip.)

1. In a medium bowl whisk together the mayonnaise and truffle oil until blended. Taste and for a stronger truffle accent, add 1/8 teaspoon additional truffle oil. (Mayo can be prepared 1 day ahead; keep covered and refrigerated.) Makes 1/4 cup

Cooking tip: White truffle oil is available in specialty food stores and online. Typically it is sold in small amounts since a little of this umami-rich oil goes a long way. However, if you can’t find it, try adding 1 1/2 teaspoons reduced sodium soy sauce instead. The soy sauce pairs well with the mushroom and onion garnishes.

Copyright Betty Rosbottom 2022