Step 1Heat a large skillet over medium heat. Add the chorizo and cook quickly until it starts to turn crisp, a minute or two. Remove with a slotted spoon and drain on a paper towel. Add the butter to the fat remaining in the pan, then add the shallots and saute until very tender, about 3 minutes.
Step 2Add the scallops and shrimp and cook, stirring constantly, until the scallops start to turn translucent. Add the oysters and cook quickly, then add the crab and swirl until heated through. Using a slotted spoon, transfer to a warm serving bowl. Add the chorizo and toss to mix.
Step 3Raise the heat to medium-high and add the vermouth. Cook, stirring occasionally, until the sauce is emulsified. Add lemon to taste, then season with pepper to taste and salt if needed. Spoon over the seafood and serve.