4 pounds snow crab clusters (legs)
4 quarts water (16 cups)
1 small onion, chopped
1 1/2 stalks celery, chopped
2 cloves garlic, quartered
2 small turnips, peeled, chopped
1/4 cup fresh chopped Italian parsley
2 teaspoons mustard seed
1 tablespoon chopped pimento
1/2 teaspoon coarse ground pepper
2 bay leaves
1/3 cup sugar-free tomato sauce
2 tablespoons half and half
1/4 cup unsalted butter
1/4 teaspoon thyme
1/8 teaspoon basil
1/8 teaspoon marjoram