Pour the cream over the mushrooms and let stand for ten minutes. Cut the peeled onion and bacon into cubes. Slowly fry the bacon over medium heat. Add the onion cubes and fry until translucent. Remove from pan and set aside.
Add oil to the frying fat. Fry the pork tenderloin in it over medium heat for 15 minutes. Salt and pepper lightly. Add the bacon, onions and cream with mushrooms. Stew in the closed pan for five minutes. Pour in the brandy and season the sauce with salt and pepper.