Boil water in a large kettle on stove or outdoor cooker. Season water with salt and your choice of above flavorings along with the juice of two lemons or 2 tablespoons of vinegar. Add potatoes and cook for 10 minutes. Add carrots, sausage and onions. Bring back to a boil. When potatoes and carrots are almost tender, add corn and crabs. Bring to a boil, then add shrimp. Cook a few minutes until shrimp are just done - they will be pink in color. Drain and pour into a basket or onto platters. Have cocktail sauce and Dijon mustard at hand.