Bring a large pot of salted water to a boil. Add the shrimp and cook until just pink, about 3 minutes. Remove the shrimp with a slotted spoon. Rinse under cold water and cool. Peel, devein, and refrigerate in a large bowl.
Bring the water back to a boil and add the lobster, head first. Cover the pot and cook for 13 to 15 minutes. Remove and cool. Remove the meat from the shell and cut into bite-size pieces.
Pick through the crabmeat to remove any cartilage. Refrigerate with the shrimp.
Dust the scallops with flour. Heat the oil in a large skillet over medium-high heat. Sauté the scallops for 1 to 2 minutes on each side, or until brown and cooked through. Remove and cool. Refrigerate with the shrimp.
In a Dutch oven, bring the wine, clam juice, shallot, and 2 cups of water to a boil. Add the salmon, lower the heat, and poach for 8 minutes. Remove and cool. Break into large pieces. Refrigerate.
Bring the poaching liquid back to a boil. Add the mussels, cover, and steam until the shells open, about 3 minutes. Remove the mussels. Discard any unopened shells, and cool the remaining shells. Remove the mussels from their shells. Refrigerate.
In a very large bowl, combine all the seafood. Being very gentle, fold in the peas, potatoes, beets, celery, onion, and apple. Line a large platter with Boston lettuce. Place the seafood on the lettuce and garnish with lemon and dill. Serve with Dill Dressing on the side.