“Gumbo is what your mama taught you,” says Janice “Boo” Macomber. “And there are as many gumbos as there are mamas.” We’re drinking Miller Lites in the cluttered kitchen at Boo’s fishing camp, a raised shack next to an alligator-infested canal that empties into southern Louisiana’s Vermilion Bay. As the sun goes down behind the brackish marsh, she ties her greying hair back with a pink bandana and sets to peeling prawns while expounding about the richly flavoured soup that bubbles on the stovetop in every Cajun household. Boo, who grew up in Abbeville, has eaten gumbo her whole life, and it’s one of the things she teaches at the New Orleans Cooking Experience, an informal culinary school for beginners.

The term “gumbo” is derived either from the Bantu “ki ngombo” for okra or the Choctaw “kombo” for filé, a Native American seasoning of finely ground dried sassafras leaves. Both make appearances in many versions of the dish. The origins of gumbo reflect the colonial-era migration of cooks and ingredients from Europe and West Africa to this low-lying state on America’s Gulf Coast. It’s a kissing-cousin of French bouillabaisse and Caribbean callaloo, but like most melting pot-dishes, gumbo lacks definitive pedigree. Okra and filé are primarily thickening agents, although they can both overwhelm more delicate ingredients, which is why some cooks leave them out entirely. Boo sums it up succinctly: “The word gumbo allows people to put anything they want in it.”

Nonetheless, there are two immutable aspects that define gumbo. All recipes start with a roux and an onion-celery-capsicum mirepoix that Boo refers to as the holy trinity. A proper Cajun roux is a different beast from its French ancestor and takes much more time and patience. Browning flour is not a technique for the inattentive cook: when added to roiling vegetable oil, it requires constant stirring to prevent scorching, or worse, the volatile spatter that New Orleans chef Donald Link calls “Cajun napalm”. A well-tempered cast-iron casserole is the best equipment for preparing gumbo. “One pot, one spoon, one plate” is Boo’s line.

Between pulls on her beer, she gradually reduces the heat as the flour darkens in hue. The finished roux, she says, should be “the colour of the bayou after a heavy rain”. It takes at least an hour to reach this stage. Sometimes I cheat by dry-browning flour in a skillet ahead of time, but my Southern roots are Huguenot, rather than Acadian; it’s not authentic and I would be banned from the bayous for claiming as much. Anyway, gumbo is about love, not sex. One requires commitment, the other is just a passing sensation. It even gets better with age, taking on gutsy complexity the longer ingredients stew together.

The onions should be allowed to sweat in the roux for a few minutes before celery and capsicum grace the pot. Then stock is introduced gradually. Don’t stop stirring, or else you’ll get lumps. (A wooden spoon proves more effective than a whisk.) This is the stage when gumbo becomes a matter of personal taste. Boo, whose daddy was a shrimper, prefers seafood over chicken-and-sausage, rabbit or duck, which are some of the other classic gumbos found along the Gulf Coast. I clean partly steamed crabs and toss in the bodies. Another hour of simmering passes and more empty beer cans are stacked on the counter. Boo is down on her knees, head deep in a cupboard filled with Zatarain’s cayenne pepper, Queen Bee “The True Cajun Queen” Seasoning and instant Community Coffee. “There’s rice in here somewhere,” she mutters. She emerges with a plastic sack of Mahatma medium-grain. It’s the standard accompaniment to gumbo, although some Cajuns like to serve creamy potato salad as an auxiliary side. Louisiana falls squarely within America’s rice-growing region. Half the year, fields throughout Acadiana – west of the Atchafalaya Basin, east of Lake Charles – are flooded for planting season. These also happen to be an ideal environment for raising crawfish, a close relative of yabbies.

“Boo,” I ask, “Do you ever put ‘crawdads’ in your gumbo?”

She turns away from the stove and peers over her reading glasses. “A sacrilege,” she says solemnly. “I never use okra or filé either. Just don’t want the flavour taking over from the shrimp, the crab. But I like bay leaves. That’s the difference between my mama’s gumbo and mine.”