Place all spice-blend ingredients in a small mixing bowl and whisk together. Set aside.
Pour flour into a skillet and toast over medium heat until golden brown and nutty, 6 to 8 minutes, stirring occasionally. Remove from heat and set aside.
Place butter into a large pot and melt over medium-high heat. Add Andouille and brown for 5 minutes. Remove from heat.
Add onion, celery and bell peppers and sauté for 4 to 5 minutes. Season with salt and pepper. Add garlic oregano, thyme, and spice-blend and continue to sauté for 2 minutes.
Stir in toasted flour and continue to stir until no lumps remain. Cook flour mixture for 4 to 5 minutes or until flour has browned slightly more. Add stock, while stirring to prevent lumps from forming. Add bay leaves.
Bring mixture to a boil and lower heat to medium-low. Simmer, covered for 25 to 30 minute or until gumbo has thickened.
Remove cover and stir in corn, shrimp, chicken, and okra. Raise heat up to medium and cook for about 5 minutes or until shrimp have just cooked through. Adjust seasonings.
Serve gumbo over rice, topped with chopped cilantro and a sprinkle of gumbo file, if using.