Pork tenderloin with creamy pepper sauce

First, finely chop the red onion. In a small saucepan, melt the butter with 2 tablespoons of sunflower oil over medium heat. Once the fat is hot, add the onion and sauté for 3-4 minutes. Then sprinkle in the flour and, stirring constantly, make a light roux (approx. 2-3 minutes).

Once the roux is ready, pour in the brandy or wine and let it simmer for about 30 seconds to allow the alcohol to evaporate. Then pour in the broth, add the thyme and whole black peppercorns. Mix thoroughly, cover, reduce heat to low, and simmer slowly for 18-19 minutes, stirring occasionally.

Meanwhile, prepare the pork tenderloin: wash it, pat it dry, remove any membranes, then season with salt and pepper and spread with Dijon mustard.