oI don't know too much about Louisianian cookery, although it's on my ever-growing list of cuisines to explore. The Gumbo Pages is a wonderful source, it's saved me from buying yet more recipe books and my bookshelves from completely collapsing under the weight of said books. Remarkable Feasts by Leslie Forbes is the only book I own with Cajun/Creole recipes, and the recipe below is basically the same as hers, with a few small differences. I think this lovely book is sadly out of print, so if you see it, buy it.
There are many, many types of gumbo, probably each having their own personal recipe, so the search for the 'proper' way to make one is fruitless. What unites this type of gumbo is the roux, the oil and flour thickener that each gumbo starts with. Unlike the French roux that you would use to make a bechemal sauce, oil or bacon fat can be used instead of butter, and you cook the flour in the hot fat until it is browned. Watch out for burns, not for nothing is it known as Cajun Napalm.
Looking at various recipes online, it seems the inclusion of a ham hock is common in a gumbo z'herbes. Leslie Forbes uses pickled pork instead, which you make yourself by macerating spare ribs in cider vinegar and spices for 24 hours. If you don't have the time or the inclination to start your cooking a day in advance, I'd advise adding a ham hock to the soup at the time that you would have added the pork.
For the pickled pork:
500 grams spare ribs
2-3 tbsps black peppercorns, crushed
2 tbsps sea salt
1 dried bay leaf, crumbled
2 dried chillies, crumbled
Cider vinegar, to cover
Put the ribs and spices in a non-reactive container (i.e. glass or plastic), and cover with the vinegar. Cover, and leave for at least 24 and up to 48 hours in the fridge.
For the soup:
3 tbsp clarified butter, oil or bacon fat
3 tbsp flour
1 small onion, chopped
2 cloves garlic, chopped
1 green pepper, deseeded and chopped
250 grams spinach, trimmed
250 grams spring greens/ kale, trimmed
1 pint chicken stock
500 grams pickled pork, rinsed and patted dry
1 tsp allspice berries
2 tsp cayenne
Freshly grated nutmeg, salt and pepper, to finish
In a large pot heat the butter, oil or fat. Add the flour and cook until lightly browned, stirring all the time. Add the onion, garlic and pepper and cook until they are softened and coated in the floury mixture. Add the spinach and greens, and cook for 10 minutes with the lid on until they have wilted down. Puree the mixture- easier with a free-standing blender or food processor, but less washing with a hand held blender. Return the gloriously green mixture to pan (if using blender or food processor) and add the pickled pork, clove, cayenne and allspice. Simmer for at least an hour until the meat can be removed from the bone with minimal persuasion. Serve over rice, or with buttered biscuits.