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 in the flour and stir continuously for 2–3 minutes to obtain a light roux.

When the roux is ready, pour in the brandy or white wine and let it simmer for about 30 seconds for the alcohol to evaporate. Add the beef broth, thyme, and black peppercorns. Mix 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 silverskin. Season the meat with salt and ground pepper, then spread the Dijon mustard evenly over it.