Purge the crawfish by soaking them in iced salt water for 30 minutes, then rinse thoroughly in a colander and discard any dead crawfish.

Fill a 20-quart stockpot with 5–6 gallons of water and bring to a rolling boil over high heat.

Stir in 2 tablespoons salt and 1/2 teaspoon cayenne pepper to season the water.

In a small bowl, combine all ingredients listed under Spice Blend and set aside.

Once the water boils, add the spice blend, 3 tablespoons liquid crab boil, and 6 smashed garlic cloves. Stir well and let the seasoned broth simmer for 5 minutes.

Add the quartered potatoes and boil for 12–15 minutes, or until almost tender when pierced with a fork.

Add the quartered onion and cook for 3 minutes, then add the halved corn cobs. Return the pot to a full rolling boil, about 3–5 minutes.

Carefully add the live crawfish to the pot, stirring gently to submerge them. Cook for 5–7 minutes, until the crawfish turn bright red and begin to float.

Turn off the heat, stir in 2 tablespoons butter, and let the crawfish, potatoes, and corn rest in the hot broth for 10–15 minutes to absorb flavor.

Using a slotted spoon or strainer basket, transfer crawfish and vegetables to a large platter or newspaper-lined table. Serve immediately with extra broth for dipping.