Pork tenderloin in pepper sauce

Start by finely chopping the onion. In a small saucepan, heat the butter and 2 tablespoons of sunflower oil over medium heat. When the fat is hot, add the onion and sauté for 3–4 minutes. Sprinkle with flour and stir continuously for 2–3 minutes to obtain a light-colored roux.

When the roux is ready, pour in the brandy or white wine and leave for about 30 seconds for the alcohol to evaporate. Add the beef stock, thyme, and black peppercorns. Stir well, cover with a lid, and simmer over low heat for 18–19 minutes, stirring occasionally.

Prepare the pork tenderloin: wash it, pat it dry with a paper towel, and trim any silver skin. Season the meat with salt and ground pepper, then brush it evenly with the Dijon mustard.