4 (6- to 8-ounce; 170 to 225g) boneless medallion steaks, such as filet mignon
1 ounce (30g) whole Zen Kampot Black Peppercorns
3 tablespoons (45mg) Zen Kampot Green Peppercorns (rehydrated for 30 minutes)
3 tablespoons (45ml) vegetable oil
1 tablespoon (15g) unsalted butter
2 thyme sprigs
1 medium clove garlic
1/2 large shallot (about 1 1/2 ounces; 40g), minced
2 tablespoons (30ml) brandy or cognac
3/4 cup (175ml) low-sodium chicken broth
3/4 cup (175ml) heavy cream or 6 tablespoons (90ml) crème fraîche
1 teaspoon (5ml) Dijon mustard
Season steaks all over with kosher salt. Set on a wire rack set over a rimmed baking sheet and allow to air-dry, uncovered, in the refrigerator for 30 minutes.
Meanwhile, crack peppercorns into rough halves and quarters. You can use a pepper mill set to its coarsest setting, a mortar and pestle or, perhaps best, a large mallet or skillet to crush them (wrap the peppercorns in a clean towel to contain them first).
Preheat oven to 375°F (190°C). Spread cracked peppercorns on a plate or in another shallow dish and firmly press one side of each steak into the pepper to encrust it in an even layer. Set each steak aside, peppercorn side up. Remaining cracked peppercorns can be saved for later use or placed in a pepper mill.
In a large stainless steel or cast iron skillet, heat oil over medium-high heat until shimmering. Add steaks, peppercorn side down, and cook until peppercorns are well toasted, about 3 minutes. Carefully turn steaks, trying not to break the peppercorn crust. Add butter, thyme, and garlic and cook, basting steaks with a spoon, until steaks are well seared on the second side. Remove from heat.
Transfer steaks to a rimmed baking sheet. Check the internal temperature of the steaks; if they've reached 125°F (52°C), they're ready to be served medium-rare. If they haven't reached their final doneness temperature (which will depend heavily on the dimensions of the steaks), transfer to the oven and continue cooking until the correct internal temperature is reached. Either way, allow steaks to rest for 5 minutes once the final doneness temperature is reached.
Pour off all but 1 tablespoon of fat from skillet and discard garlic and thyme. Add shallot and the rehydrated whole green peppercorns, return to medium heat, and cook, stirring, until shallot is tender, about 2 minutes.
Add brandy or cognac. (To prevent an unexpected flare-up if working over gas, you can turn off the burner, add the alcohol, then reignite the burner.) Cook until raw alcohol smell has burned off and brandy has almost completely evaporated.
Add chicken stock and bring to a simmer, stirring and scraping up any browned bits. Whisk in cream or crème fraîche, then simmer, stirring often, until sauce has reduced enough to glaze a spoon. Whisk in mustard. Season with salt.
Arrange steaks on plates and pour sauce on top. Serve with your favorite steak side dish.