4 ears corn, husks removed and ends trimmed, each cut into 4 equal pieces
2 lb frozen cooked crawfish, thawed
2 lb frozen cooked shell-on snow,
Dungeness or blue crab, thawed and chopped into 4-inch pieces
1 1/2 lb raw frozen and thawed zipperback jumbo shrimp (NOTE: Zipperback shrimp come deveined with shells intact.)
1/3 cup chopped fresh parsley
2 lemons, cut into wedges
4 dried bay leaves, slightly crumbled
2 tbsp yellow mustard seeds
1 tbsp coriander seeds
1 tbsp whole allspice
1 tbsp dill seeds
1 tbsp black peppercorns
1 tbsp red pepper flakes
2 tsp fennel seeds
1 tsp whole cloves
Fit a 12-qt stockpot with a large strainer basket and fill with 4 qt water. (Alternatively, skip the strainer basket and use a wide, heavy skimmer to remove shellfish and vegetables after cooking.) Add salt.
Prepare seasoning: In the center of a 10-inch square cheesecloth, pile all seasoning ingredients. Gather corners of cheesecloth, tie securely with kitchen string and add to stockpot.
Add potatoes, garlic, onions and lemon halves. Cover and bring to boil. Reduce heat to a simmer and cook for 20 minutes.
Add corn and return to a simmer. Cook until corn and potatoes are tender, about 5 minutes. Add crawfish, crab and shrimp and bring to boil. Turn off heat, cover and let stand for 10 minutes, until all ingredients are heated and shrimp is cooked through.
Remove strainer basket from pot and drain, discarding spice bag, lemons, garlic and onions. Divide shellfish-corn mixture among bowls. Sprinkle with parsley and serve with lemon wedges.