Veal can also be used with this dish and in Italy fresh porcini would be the mushroom choice.
Grill beef on hot plate until just brown on the outside.
Add olive oil and minced garlic to a frypan and heat.
Add mushrooms and toss for 4 minutes.
Add stock and balsamic vinegar.
Simmer for 3 minutes.
Slice beef into 1 ½ - 2cm slices and plate.
Crack coarse fresh pepper on top.
Pour sauce over and add shiitake mushrooms on top.