Begin by prepping the cubeb peppercorns. Place them in a spice grinder or a mortar and pestle and crush them coarsely. Set aside.

Season the filet mignon steaks generously with salt and then coat them with the crushed cubeb pepper on all sides, pressing it in gently to adhere.

In a large skillet, heat 1 tablespoon of olive oil over medium-high heat. Add the shallots, cut side down, and char them for about 3-4 minutes until they are golden brown. Flip them and cook for an additional 2 minutes. Remove the shallots from the skillet and set aside.

In the same skillet, add the remaining tablespoon of olive oil. Increase the heat to high and add the seasoned filet mignon steaks. Sear them for 4-5 minutes on each side for medium-rare, or longer if desired. Use a meat thermometer to check for doneness (130°F for medium-rare). Once cooked to your liking, remove the steaks from the skillet and let them rest for 5-10 minutes.

Lower the heat to medium and deglaze the skillet with cognac, scraping up any browned bits. Allow it to simmer for about 2-3 minutes until slightly reduced.

Add the beef stock to the skillet and continue to simmer for another 5-7 minutes until the sauce thickens slightly.

Remove the skillet from heat and whisk in the butter until melted and incorporated. Stir in the chopped tarragon and season the sauce with salt and freshly cracked black pepper to taste.

To serve, place the rested filet mignon on a plate, drizzle with the cognac and tarragon reduction, and arrange the charred shallots alongside.