Directions

For the sauce

1. Melt the ½ tablespoon of cold butter in a medium saucepan over medium heat. Add the onion and cook, stirring often, until browned, 8 to 10 minutes. Stir in the green peppercorns and cook for 1 minute, then pour in the cooking wine and cook, stirring often, until half the liquid has evaporated, about 1 minute. Stir in the cream, vinegar, Worcestershire, and Kitchen Bouquet. Reduce the heat to low and cook, stirring often, until the liquid has reduced by half, about 5 minutes.

2. Turn off the heat and set the sauce aside to cool for 10 minutes, then pour it into a blender. Add the cheese and the butter with the motor running and blend until the sauce is smooth, about 30 seconds. Transfer to a small saucepan and set aside. The sauce can also be refrigerated in an airtight container for up to 1 week.

For the burgers

1. Place the ground beef in a large bowl and gently use your fingers to fluff the meat to loosen it (you don’t want to overhandle the meat). Set a 4½- to 5-inch metal ring (or make a “collar” by folding a long piece of aluminum foil into a 1-inch strip and taping it into a 4½- to 5-inch circle) on a plastic wrap–lined cutting board. Place one-quarter of the meat in the ring, using light pressure to create a perfectly even and not-too-packed ¾-inch-thick patty. Carefully remove the ring and repeat with the remaining beef to make 4 patties. Mix the salt and pepper together in a small bowl and use half of it to season the tops of the burger generously.

2. Heat a cast-iron flat-top griddle or large cast-iron skillet over medium-high heat for 2 minutes. Dip a folded paper towel in the oil and use it to grease the pan (you won’t use all the oil). Use a spatula to carefully transfer the patties to the pan, seasoned-side down. Sprinkle the patties with the remaining salt and pepper mixture. Cook without pressing down or moving the burgers until the bottoms are browned, about 5 minutes. Flip the burgers over and continue to cook for 4½ to 5 minutes longer for medium-rare or 7 minutes more for medium. (If, after flipping, there is a lot of rendered fat in the pan, carefully tilt the pan and spoon or pour it out—otherwise, the burgers will steam rather than sear.) Sprinkle each burger with 2 tablespoons of the blue cheese, then cover the pan until the cheese has melted, about 1 minute. Transfer the burgers to a plate.

3. Pour off most of the fat from the pan and use a paper towel to wipe out the browned bits. (Alternatively, heat a second pan or griddle and grease it lightly with the remaining oil.) Open the buns and place the bottom halves cut side down in the hot pan and cook until browned and toasted, 1 to 2 minutes. Turn the buns over to toast the other side, 30 seconds to 1 minute longer. Place each bun half on a plate, then repeat with the bun tops.

4. Transfer each patty to a bottom bun half and cover with the top bun. Warm the peppercorn sauce over medium heat, stirring so it doesn’t burn at the bottom. Serve the burgers with lettuce, a tomato slice, and a pickle spear, with the peppercorn sauce on the side.