Shuck, rinse and cut the ends of the corncobs flat. Stand upright and use a sharp knife to remove the kernels from the cobs. Reserve corncobs. In a large Dutch oven heat the oil and add the clams, shrimp, sausage and onions. Stir with a wooden spoon for 2 minutes. Add the seasoning, wine and broth. Bring to a boil, and when shrimp float to the surface (about 1 minute), remove from the pot. Remove clams after they open, then remove the sausage. Add potatoes and cook for 20 minutes (until tender), and then remove with a slotted spoon. Return broth to a boil and add corn kernels, cold butter and lemons. Simmer for 5 minutes. Adjust seasoning to your liking.
When ready to serve, reheat cooked seafood one item at a time by placing them back into the broth. Use a slotted spoon to divide them evenly – placing them into individual serving bowls. Repeat with potatoes and sausage. Return broth to a boil and add the chopped parsley. Spoon 6 ounces of broth over each serving. Use a slotted spoon to divide corn kernels and lemons evenly among the bowls. Serve with toasted French bread.
Corn & Clam Broth
Place corncobs in an 8-quart stockpot and cover with water. Add clam juice, onions, and celery, bring to a boil, reduce heat to medium low and simmer for 1 hour. Tie spices tightly in cheesecloth with a string. Tie this spice pouch to the pot handle for easy removal. Let simmer another 20 minutes. Strain, reserve the liquid, and discard cobs.