Place the wine, onion, carrot, celery, peppercorns, and bay leaves in a poacher just big enough for the salmon. Bring to a boil and simmer for 3/4 of an hour.
Slide the fish into the poacher and add boiling water just to cover the fish. Cover the poacher and barely simmer until the fish is cooked, about 13 minutes per inch of thickness.
Add the shrimp in the last few minutes and poach until done. Remove from heat and cool salmon in the poaching liquid. Remove the shrimp, shell and devein and set aside.
Carefully lift the salmon from the poacher and place on a serving platter. Surround with cucumber slices and shrimp. Garnish with tarragon.
To make the herb sauce: Combine the mayonnaise, lemon zest, lemon juice, yogurt, and sour cream. Stir in the garlic, parsley, tarragon, and chives. Place in a small bowl and serve with salmon. Makes 1 1/3 cups sauce.