Basic Seafood Gumbo

Name: Basic Seafood Gumbo
Ingredients: 1 1/2 cups crab meat; 2 pounds shrimp (in shells); 3 quarts water; 2 small bay leaves; 1 teaspoon lemon juice; 1 small onion (cut into wedges); Salt to taste; Black pepper to taste; 1 teaspoon parsley (or to taste); 2 pounds okra (sliced); 4 tablespoons bacon grease, or butter or duck fat (divided); 4 tomatoes (peeled and chopped); 2 onions (finely chopped); 2 green peppers (finely chopped); 1/2 teaspoon crushed red pepper (or to taste); 4 tablespoons brown roux (see recipes, below); Optional: salt, pepper, thyme, parsley, to taste; Optional: Rice (cooked)