For the bay seasoning:
In a large bowl, combine chili powder, paprika, cayenne pepper, bay leaves, oregano, salt, sugar, dry mustard, thyme, black pepper, white pepper, and coriander seed and set aside.
For the Crabs:
Inside a large pot, place an expandable steamer basket on the bottom. Add the beer, vinegar, and enough water to come up to the bottom of the basket. Cover the pot and bring to a boil. Carefully transfer the crabs with tongs to the basket, spritz with fresh lemon juice, and toss in the lemons. Sprinkle bay seasoning, to taste, over each layer of crabs (about 1/4 to 1/2 cup).
Cover the pot tightly and steam until the crabs are cooked through, about 10 to 15 minutes. (To check doneness, remove a crab leg, break open, and taste.)
Melt the butter in a small saucepan. Add lemon juice, salt, and pepper sauce. Remove from the heat, adjust seasoning to taste, and serve as a dipping sauce for the crabs, bread, and corn.
Yield: 4 to 6 servings