1. Peel and cut the potatoes into small cubes and place them in a saucepan with water. Water should cover the potatoes. Add a little salt and boil over medium-high heat.

TIP (When we want to boil roots and bulbs we always start boiling them with cold water so as not to destroy their starch and have uniform baking).

2. Season the tenderloin with the mustard, salt, pepper and paprika.
3. Heat a frying pan and add the olive oil. Once it is hot, place the tenderloin inside and shield well from all sides.
4. Once it is well shielded, remove from the pan and set aside to rest.
5. On a cutting board, cut the mushroom into thin slices and finely chop the leek, garlic, rosemary leaves, chives and onion.
6. In the pan we used for the tenderloin, add a little olive oil and add the leek and the onion. Sauté until withered. Then we put the mushrooms cut into slices and the chopped garlic.
7. When the vegetables have been cooked properly, add the meat, mustard and quench with the red wine and the worcestershire sauce. Cover the pan.
8. Let it cook over medium heat. Once it is ready add the chopped leaves of rosemary, salt and pepper.
9. As soon as the potato boils, drain it well. Add the butter and cream, stirring very well with a whisk. At the finish we put a little olive oil, salt, pepper and the chives.
10. Cut the tenderloin into thin slices and serve with all your preparations.