Preheat the oven to 300°F. Cut leek in half lengthwise and rinse well. Then cut in half crosswise.
In a medium saucepan, combine 6 cups cold water, leek, carrot, celery, bay leaf, parsley, peppercorns and 1 teaspoon salt. Bring to a boil and simmer for 15 minutes. Add wine and simmer 5 more minutes.
Rinse salmon and place in a 3-quart glass baking dish, skin side down. Season with salt and pepper. Pour in enough of the hot poaching liquid to completely cover the fish. Discard excess liquid, if any. Place baking dish on a baking sheet to catch any drips, cover tightly with aluminum foil, and transfer to oven for 10 minutes. Remove from oven, remove foil, and let sit for 10 more minutes. Transfer salmon fillets to a platter and discard liquid. Cover with plastic wrap and refrigerate until ready to serve (the salmon can also be served warm). The salmon can be made one day ahead of time.
Remove skin by carefully holding the salmon in the palm of your hand, skin side up. Slide a paring knife between the skin and the fillet, and slowly peel the skin back. Arrange salmon fillets on a platter garnished with pea shoots. Serve with Green Sauce