Pork Tenderloin in Pepper Sauce

First, finely chop the onion. In a small saucepan, heat the butter with 2 tbsp sunflower oil over medium heat. Once the fat is hot, add the onion and sauté until translucent for about 3–4 minutes. Then stir in the flour and, stirring constantly, make a light roux (about 2–3 minutes).

Once the roux is ready, deglaze with brandy or white wine and simmer for about 30 seconds to allow the alcohol to evaporate. Then pour in the beef stock, add thyme and black peppercorns. Stir everything well, put on the lid, reduce the heat and let it simmer gently at a low temperature, stirring occasionally, for 18–19 minutes.

Meanwhile, prepare the pork tenderloin: Wash the meat, pat it dry, remove any sinews, season with salt and pepper, and generously coat all around with Dijon mustard.