Pre-heat broiler. Season the salmon fillet well with salt and pepper. Wrap 3 of the bacon slices, evenly spaced, around the salmon filet. Place fillet on roasting pan, and place under broiler. Cook until just done (about 10 minutes).
Meanwhile, prepare the sauce. Cut the remaining two slices of bacon into small squares. Place in a heavy saute pan over high heat. Cook until medium-brown, about 2 minutes. Spill out all but 1 teaspoon of the bacon fat. Lower heat to medium-high. Add the shiitake mushrooms, stir well, and saute until mushrooms become golden-brown, about 3 minutes. Turn heat down to medium, and stir in garlic and parsley. Cook for one minute. In a bowl, combine the oyster sauce with 1/4 cup of hot water. Blend, and add to saute pan. Cook one minute over medium heat. Season well with nutmeg.
To serve, remove the wrapped bacon from the salmon (you may discard the bacon, or use it as a garnish). Delicately slice the salmon along the natural separations, and divide among 4 plates. Top each with a quarter of the sauce, and with a flat parsley leaf for garnish.