Crawfish are very high on my list of favorite things to eat. Some people are going to tell you that they need to be purged by pouring salt on them and then swishing them around in water with the salt. This makes them, uh, void themselves, and then you are left with a better tasting animal. We never did this. Some places are sorta scummy, and make scummy tasting crawfish. You can't purge the taste of where they lived out of them. Get them from a cleaner spot, and they will be fine.
Now I have to say here, "clean" and "clear" are not exactly synonymous. Just because water is clear does not make it clean, as a lot of people seem to think. Suspended particulate is not unexpected in some systems, depending on factors like gradient, water exchange rates, and substrate. Think of it like this... which is going to be cleaner, a clear stream running through a city, or a muddy stream running through a forrest? If you get a bunch of crawfish that you think taste a bit odd, don't get them from there next time.
And so you got a bunch of crawfish. Wash them off till the water runs off them clear, like you would do with rice. Fill a pot with enough water to cover them completely (but don't put them in yet!) and bring it to a rolling boil. Add a season mix consisting of LOTS of mustard seed, along with paprika, cayenne, white and black pepper corns, several bay leaves, allspice, cloves, celery seed, and a little salt. Also add a couple tablespoons of white vinegar, as this will make the crawfish easier to pick. Potatoes can go in and cook 15 minutes before the crawfish. Put in a few ears of corn a few minutes before the (live) crawfish, and boil it all an extra 12 to 15 minutes. No more than that, or the crawfish get strange. I go just a touch less myself, about 11 minutes.
Pour it out through a strainer, let it cool a minute or two, and cover your table with paper. Butcher paper is best, but some people use things called "newspapers." (Newspapers are anachronistic items purporting to deliver editorial, journalistic and entertaining content to persons hesitant to concede the death of the twentieth century.)
Dump the whole shebang out on the table, and get to work. things will be a bit messy, it is not just you.
Remoulade is nice with crawfish. I like a good light pilsner or lager style beer as well. Lots of people will have a nice light white wine with crawfish, nothing wrong with that, we are not here to judge.
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