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 and very soft, 35 minutes. Deglaze with the beef consomme; 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. Season the beef with the worcestershire, salt (for a crusty coating) and pepper. Using a box grater, grate 3 to 4 tbsp. of the peeled onion over the meat (this flavors the meat and keeps the burgers moist). Add the parsley. Mix the meat (dont overwork) and form 6 patties thinner at the center than at the edges. Drizzle with EVOO. Cook, turning once, for 6 to 8 minutes for pink centers.
Serve the burgers on the buns, topped with the sauce, potato chips and pickles.