Make sauce first,i use small size fresh shitake ,incase use big fresh one first slice it ,slice shallot,finely chop garlic
Fry chopped garlic,onion with butter on low heat until light brown
Add mushroom ,fry until cook ,get good smell
Seasoning with brown sauce powder ,salt and pepper just to taste,not all
Add whipping cream, stir to mix..let it boil if that too thick add milk ,let it cook 3 more mins ,add parsley,heat off
Heat grill pan on medium ,clean and pat dry pork loin ,seasoning with salt and pepper, olive oil..grill approximately 7 mins per each side ,depend on how thick..may be more ..flip and grill until golden ,transfer to cutting board ,let sit 3 mins
Grill bell pepper and onion on same old grill pan until lightly brown
Set on serving plate by slice or not as you desire,top with warm mushroom sauce,side with fresh green salad and some choice of pasta (option )
