In a heavy skillet, melt the shortening over mod-low heat. Add flour and cook the roux, stirring constantly, for 30 minutes, or until it is the color of cocoa. Stir in the onion and cook, stirring until onion begins to brown. Add okra and cook over moderate heat, stirring frequently, until okra is golden. In a kettle, bring 8 cups water to a boil, add the roux mixture, ham, tomatoes, with juice, bell pepper, garlic paste, bay leaf, parsley, thyme, and celery leaves. Simmer the mixture, stirring occasionally for 50 minutes. Stir in the shrimp and lump crabmeat and simmer for 5 minutes or until shrimp are firm. Season it with cayenne and salt. Discard bay leaf and serve the gumbo sprinkled with file powder. Makes about 9 cups. a 1945 Gourmet Mag. favorite.