If you’re a fan of traditional French onion soup – and who isn’t? – you’re going to love this burger. It’s kitted out with all of the ingredients that make the soup such a treasure – tender, browned onions, beef broth, red wine, Gruyere cheese, and French bread – and finally lathered up with mustard mayo. Rich and full of flavor, this burger is the perfect entrée for a special holiday meal, summer or winter.
Prepping it, however, does require a bit of care. The onions need to be cooked low and slow so that they’ll soften and brown properly. (You can, however, cook them a full day ahead, then cover and chill them until the moment of truth.) Likewise, you want to keep a strict eye on the burgers as they cook. Overdo it and they’ll end up dry.
You’re welcome to buy whichever kind of burger strikes your fancy, but please resist the siren call of pre-packaged quarter-pounders. They’re too thin for this recipe and will definitely end up overcooked. If you’re up for a little extra work, you can “grind” your own meat by buying the beef of your choice – skirt steak, short ribs, sirloin, you name it — cutting it into one-inch cubes, freezing it for 40 minutes, and finally pulsing it (in two batches) in a food processor until you reach the ground beef texture you desire.
In the classic recipe, a slice of French bread is floated on the soup’s surface like a bowl-wide crouton. Here that bread provides the coziest of beds for a juicy burger. (In truth, though, that bread — lightly brushed with garlic butter and browned in the oven — is fairly amazing all by itself.)
Start to finish: 1 hour (40 active)
4 tablespoons butter
3 cups packed thinly sliced onion
1 ½ teaspoons minced garlic
1 teaspoon fresh thyme leaves
1/3 cup beef or chicken broth or water
four 4-inch pieces of French bread, cut in half
1/3 cup mayonnaise
1 ½ teaspoons Dijon mustard
2 tablespoons vegetable oil
1 ½ pounds ground beef, shaped into 4 oblong burgers, to fit the size of the baguette “buns”
4 ounces thinly sliced gruyere
1/3 cup red wine
In a large skillet heat 2 tablespoons of the butter over medium high heat. Add the onion and a pinch of salt, reduce the heat to medium low and cook, covered, stirring occasionally, until the onion is very tender, about 15 minutes. Remove the lid and continue to cook the onion, uncovered, stirring frequently, until the onion is golden brown, about 15 minutes. Add 1 teaspoon of the minced garlic and the thyme and cook, stirring, 1 minute. Add the beef broth and cook, stirring the onions constantly to scrape up the glaze at the bottom of the pan, until most of the liquid has been absorbed. Transfer the mixture to a bowl, add salt and pepper to taste and set it aside. Clean and dry the skillet and return it to the burner.
While the onions are cooking, preheat the broiler. Melt the remaining 2 tablespoons butter with the remaining ½ teaspoon garlic. Brush the cut sides of the French bread liberally with the garlic butter and on a sheet pan broil the bread cut side up, 4 inches from the heat source, until it is golden, about 2 minutes. Remove from the oven and transfer the French bread halves to each of 4 plates. In a small bowl stir together the mayonnaise and the mustard and spread the mixture evenly on all the cut sides of the bread.
In the skillet, heat the oil over high heat. Season the burgers on both sides with salt and pepper and add them to the pan. Reduce the heat to medium high and cook the burgers until they are nicely browned (but not cooked through) about 3 minutes a side, Remove the skillet from the heat, spoon off and discard all but 1 tablespoon of the fat in the pan and top each burger with one fourth of the onion mixture and one fourth of the cheese. Pour the wine into the skillet and put it back on the burner. Reduce the heat to medium, cover the skillet and cook the burgers just until the burgers are cooked to medium rare and the cheese is melted, about 2 to 4 minutes.
Transfer the burgers to one of the French bread halves on each of the plates. Simmer the liquid in the skillet, scraping the bottom of the pan, until it is syrupy and spoon some of it over each burger. Top with the remaining French bread half and serve right away.