Preparation

• Finely chop the onion, ensuring that the pieces are uniform to facilitate cooking.
• Mince the garlic finely, taking care not to lose any part to make the most of its flavor.
• Very finely dice the carrot, trying to keep the pieces a similar size so they cook evenly.
• Thoroughly clean the leek, removing the harder green part, and chop it finely.
• Pat dry the tenderloin with a paper towel to remove any traces of blood, ensuring it is completely dry to facilitate searing.
• Season the tenderloin evenly with salt and pepper to taste.
• Add a generous drizzle of oil to the pan and heat over medium-high heat until it's very hot.
• When the oil is very hot, sear the tenderloin on all sides for about 4-5 minutes until golden. Remove and set aside.
• Lower the heat to medium-low and, in the same oil in the pan, cook the vegetables for about 10 minutes, stirring occasionally.
• Meanwhile, finely chop the celery so it's ready to add to the pan.
• When the vegetables have been cooking for about 20 minutes, add the celery and let it cook for another 40 minutes on low heat, stirring occasionally.
• Add the thyme sprigs, bay leaf, and pieces of chocolate to the pot, mixing well.
• After 10 minutes, add a good splash of aged wine and let it cook for another 30 minutes to allow it to reduce slightly.
• Add the chicken broth and let it cook for 40 minutes on low heat, allowing the flavors to blend.
• Return the tenderloin to the pot, cover it, and let the meat cook for 30 minutes on very low heat.
• Turn off the heat and let the stew rest, covered, for 15 minutes so the flavors concentrate.
• Transfer all the cooking juices to the blender jar, add the teaspoon of mustard, and blend until a fine and homogeneous sauce is obtained.
• Optional: Toast the pine nuts in a pan without oil for 3-4 minutes, until they acquire a golden color.
• Optional: Add the pine nuts, dried apricots, and prunes to the pot and let it cook for another 10 minutes so their flavors integrate.
• Slice the tenderloin into rounds about 2 cm thick, place them on a platter, and pour the sauce over them.
• We can also return the sliced and arranged pork tenderloin to the casserole to serve directly at the table, ensuring it is well covered by the sauce.