Put the scallion, lemon slices, bay leaf, peppercorns, and white wine in a large skillet. Add water to half fill the skillet, and bring to a boil. Boil for 2 minutes, and then reduce the heat to its lowest setting. Add the salmon pieces, cover the skillet, and let simmer for 8 minutes. Remove the skillet from the heat, keep covered, allow the salmon to cool in the cooking liquid.
Meanwhile, melt 1 oz of the butter in a large skillet over medium heat. Add the smoked salmon, scallions, and nutmeg and stir for about 2 minutes until the salmon looses its shiny coral color and becomes opaque. Remove from the heat and set aside until cool.
Drain and flake the poached salmon and put into a wide, shallow bowl. Add the smoked salmon mixture and cooking juices. Add the rest of the butter. Use your fingers to gently mix it all together until the salmon is very finely mixed. Stir in the parsley. Add salt and pepper to taste. Spoon into a bowl, cover, and chill until 30 minutes before you are ready to serve.
When ready to serve, preheat broiler to high. Toast the bread on both sides until golden brown and crisp. Spread the pâté on the hot toast.