For crab seasoning: add 4 tablespoons mustard seeds, 3 tablespoons of coriander seeds, 1 tablespoon of dill weeds, 1 tablespoon of ground allspice, 1 tablespoon of cayenne pepper, 1 teaspoon black pepper and 1 teaspoon sugar in a bowl and mix well.
Heat pot with oil over low fire. Add 4 onions, 1 thumb of ginger, 1 whole garlic and sauté till fragrant. Then, stir in seasoning mix and 4 basil leaves, and quickly fill in water until 2/3 full. Increase heat to medium fire, and bring to a boil.
Squeeze the lemon wedges and drop it into the pot. Add 4 bay leaves and 1 tablespoon of salt.
Add 3-4 small potatoes and boil for 10 minutes. Add 1 ear of sweet corn and boil for 15 minutes.
Add 2 tails of crayfish and allow to cook for 5-8 minutes. Add in 300 grams of clams, 1 kilograms of prawns and 1 crab. Cover with a lid and cook for 3 mins. Turn the heat off, and allow the remaining heat to cook for 10 minutes before removing.
Lay sheets of large parchment papers (or newspapers) on the table. Using a skimmer, retrieve all the seafood and vegetables, and place atop. Melt 2 knobs of butter on the hot seafood, garnish with ground pepper and chopped basil and serve.