In a tall 12-quart pot with a boil basket, add the butter, lemons, mustard seeds, salt, cloves, allspice, coriander, cayenne, bay leaves, potatoes, corn, sausage, onions, and garlic. Fill the pot with water two-thirds up the sides. Turn heat on high. When the water gets warm (but before it’s boiling), taste the water and make any spice adjustments, such as adding more salt or cayenne.
Meanwhile, as the water is heating, purge the crawfish if they haven’t been purged yet. (Purging is getting rid of all the mud and other swamp gunk). To do this in an apartment, put a stopper in your kitchen sink, unload the crawfish into the sink, and fill it with water. Let them soak for 2 minutes and then drain the sink. The water will be brown and kind of funky, but after you repeat this action 2 more times the water should be more or less clear.
Once the pot is boiling, throw in the crawfish and boil for 10 minutes, turn off the heat and let sit for 15 minutes. (You can do this in batches, just add more water and spices as necessary. The corn and potatoes can come out of the pot after the first batch is boiled.)
Place bowl of crawfish on table covered with newspaper or butcher paper, snap, peel, and enjoy.
For condiments, Louisiana hot sauces such as Tabasco or Crystal are appropriate, though I’ve found Mexican Cholula, while untraditional, adds both heat and smokiness to the meat. Melted garlic butter, lemon juice, and cocktail sauce also go well with the crawfish. For the boil, I like to use my own spices but most people use a commercial spice mix for a boil, such as Zatarain’s or TexJoy. If you order live crawfish, however, the seller will usually include some crawfish boil spice mix in your package.