· 3 tablespoons butter
· 5 onions, 4 thinly sliced and 1 peeled
· 1 bay leaf
· 1/2 teaspoon ground thyme
· 1 cup beef consommé
· 1 1/2 cups sour cream
· 2 pounds ground beef sirloin
· 6 brioche buns, split
· 36 good-quality ridged or thick-cut potato chips, preferably cooked in olive oil
Heat the butter in a large skillet over medium heat. Add the sliced onions and bay leaf; season with salt, pepper and the thyme. Cook, stirring occasionally, until deep caramel in color and very soft, 35 minutes. Deglaze the pan with the beef consommé and cook until all the liquid is almost absorbed. Let cool, then discard the bay leaf. Stir in the sour cream.
Preheat a griddle or large cast-iron skillet over medium-high heat. Place the beef in a bowl and season with the Worcestershire, salt (for a crusty coating on the burgers) and pepper. Using a box or hand-held grater, grate 3 to 4 tablespoons of the peeled onion over the meat (the grated onion and its juice will flavor the meat itself, plus keep the burgers moist as you cook them). Add the parsley. Mix the meat, but do not overwork it. Form 6 patties, thinner at the center than at the edges for even cooking. Drizzle with EVOO. Cook the burgers, turning once, for 6- 8 minutes for pink centers.
Serve the burgers on the bun bottoms and top with the sour cream sauce, potato chips, a couple of pickles each and the bun tops.