Crawfish are freshwater cousins to lobsters and shrimp. Like their other shellfish kin, they are beloved for their sweet and savory flesh. In the United States, Louisiana is the heartland of crawfish production and consumption. Both wild-caught and farmed crawfish are available from numerous suppliers, live and raw, or cooked. Cold cooked crawfish are tasty just as they are. They're still good when reheated, but it must be done carefully to preserve their texture.
Boiling Water Method
Thaw the crawfish overnight in your refrigerator, spreading them in a single layer, if possible. Thawing at refrigerator temperature helps guarantee food safety. The next day, boil a large pot containing at least a gallon of water for each pound of crawfish. Drop the thawed crawfish into the pot and wait for it to return to a full boil. Remove the crawfish after a minute of boiling time and peel one. If it isn't hot all the way through, return the crawfish to the pot for another 45 seconds. Repeat the process until the crawfish are fully heated, then serve.
The steamer method works much the same way as the boiling water method. Arrange the crawfish in a shallow layer in the basket of an electric steamer or a pot with a steamer insert. Bring the steamer to boiling and time the crawfish for 10 minutes. Open the steamer, taking care not to scald yourself with the hot steam. Remove one crawfish and peel it to see whether it's hot all the way through. If not, steam for another five minutes. The steamer method can also be used to reheat crawfish tails. Steam those for six minutes before testing.
Saute crawfish gently in clarified butter or olive oil. The direct heat of a skillet isn't as gentle as the wet heat methods, so use a moderate temperature and pay close attention to the crawfish so they don't overcook. Heat the butter or oil with minced onion, garlic or crawfish boil seasoning, then add the crawfish to the pan. Saute them for three to four minutes, tossing them regularly so all sides are heated and seasoned. Remove the pan from the burner and let the crawfish sit, covered, for two to three minutes.
If you're working with your own leftover crawfish, refrigerate or freeze them as soon as possible after cooking to preserve food safety. If they sit out at room temperature for four hours after cooking, they should be discarded. If you're buying cooked crawfish, work with a reputable supplier. Don't buy undated thawed crawfish or frozen crawfish that show signs of having been thawed and refrozen. Don't reheat crawfish that smell "fishy," which is a sign they're not fresh. Once crawfish have been reheated, discard any leftovers.