Pack the ground sirloin into two 1/2 lb burgers. Form them well, but not too tightly. Let them breathe a little. Chop the shallots, thyme, and mince the garlic.
If a mortar and pestle is available, crush the black peppercorns, but leave many whole so they are all different sizes, in order to achieve a variant pungency (his words).
Heavily pepper the burgers on both sides and salt them, to form a little crust.
In a wide pan with high sides (cast iron is great), warm a drizzle of olive oil and one tbsp of butter over medium high heat. Add the burgers in and sear for 4-5 minutes on each side. Set aside.
Lower the heat to medium and add the rest of the butter. Saute the diced shallots and garlic for about a minute or so.
Add in a handful of the peppercorns (not as much measuring here), and the beef stock and simmer for a few minutes. Add the brandy and raise the heat to cook off the alcohol for a few minutes.
Now, add ½ cup of the cream and keep whisking until the sauce thickens. It's a good idea to keep adding in a little more peppercorn here and there to achieve the proper "au poivre."
Add more cream if you like the sauce on the lighter side of chestnut colored. The thyme can go at this point as well, followed by the burgers.
As the burgers finish in the sauce for a couple minutes, make sure to baste them with the now luscious sauce.
Toast the buns lightly and serve the burgers with additional sauce on top. The sauce should ideally and flirtatiously drip down the sides of the burger. Never too much of this good thing. French style. New York portions.
