Shrimp and Oyster Gumbo

1/2 cup vegetable oil
2 tablespoons all-purpose flour
4 to 5 medium onions, chopped
2 to 3 cloves garlic, minced
2 (16 ounce) cans tomatoes
4 cups fish or chicken stock
2 pounds raw shrimp, peeled and deveined
2 bay leaves
1 tablespoon seafood seasoning
2 (10 ounce) packages frozen okra
Salt and pepper, to taste
1 to 2 pints oysters, undrained
1 tablespoon gumbo file
Cooked rice

Heat oil in a heavy saucepan or Dutch oven over medium heat; add flour very slowly, stirring constantly with a wooden spoon until flour is very brown.

Add onion and garlic; cook until onion is soft but not brown.

Add tomatoes, fish stock, shrimp and bay leaves; simmer for 30 minutes, stirring frequently.

Add seafood seasonings; simmer for 45 minutes.

Add okra, salt and pepper; continue to simmer for 5 minutes.

Add oysters and simmer 10 minutes or until edges of oysters curl. Just before serving, stir in gumbo file.

Serve over rice.