In a large square-head roasting pan (approximately 20 by 17 by 7-inches), with handles on each side, combine the water, salt, beer, and crab boil and bring to a boil. Add enough seaweed to cover the bottom of the pan, about 1/2 of the seaweed. Arrange the onions and potatoes around the seaweed. Cover tightly with a lid or heavy aluminum foil, lower the heat, and steam for 10 minutes. Add the corn, garlic, artichokes, sausages, and lobsters. Sprinkle with the Essence and cover with the remaining seaweed. Add enough water if needed to cover the bottom of the pan. Cover tightly, and steam until the lobsters are red, 20 to 30 minutes.
Remove the lobsters from the pan and break open over a bowl. Place the lobsters over a platter. Add any lobster liquid to the pan. Arrange the clams, mussels and asparagus over the seaweed, cover tightly, and steam until the clams and mussels are open, 10 to 15 minutes.
Turn off the flame. Discard any unopened clams and mussels. Transfer the items to platters or bowls for transporting to the table or picnic area.
In a small saucepan, melt the butter. Add the lemon juice and cayenne, to taste. Divide among small bowls or containers for dipping the seafood. Serve with French bread.
Yield: 8 to 10 servings