For best results, take the beef tournedos out of the fridge and let sit for 30 minutes before cooking.
In an oven-safe skillet, heat the butter and oil. Add tournedos and sear on each side for about 2 minutes or until golden brown. Sear the bacon.
In a preheated oven to 375°F, continue cooking the tournedos until the desired doneness. When ready, set them aside on a plate.
Return the pan to the stove. Add the garlic and sauté for 30 seconds. Add the vinegar and mushrooms. When the mushrooms are cooked, add the cream, season with salt and pepper.