1. Cut the meat into pieces and heat the oil + butter mixture.
2. Brown the meat in the oil + butter mixture in a casserole dish.
3. Remove the pieces from the casserole dish and discard the excess fat.
4. Deglaze the casserole dish with white wine, bouillon cube, mushroom juice, and cream (2/3 of the jar).
5. Spread the pork tenderloin with Dijon mustard and put it back in the casserole dish with the mushrooms.
6. Cook for about 30 minutes over very low heat.
7. At the end of cooking, add the remaining cream, salt, and pepper.
8. Enjoy your meal.