Pour the canola oil into a heavy Dutch oven and set the burner to medium heat. Let the oil warm for a minute or two until it shimmers slightly across the surface.

Whisk in the flour and stir constantly, scraping the bottom of the pot with every pass. Watch the mixture move from a pale, sandy paste through tan, peanut butter, and finally a deep chocolate brown, with a roasted, coffee-like aroma signaling it is ready.

Add the chopped onions, green bell peppers, and celery directly into the hot roux. Listen for a sharp crackle as the vegetables hit the pot, and stir until they soften and turn translucent.

Stir in the andouille and smoked sausage, mixing everything together for about 3 minutes. The sausage should pick up a little color and release its smoky fat into the vegetables.

Sprinkle in the Creole seasoning, thyme, garlic powder, and onion powder, stirring to coat everything evenly. The spices should smell fragrant and slightly toasted as they hit the hot pot.

Pour in the seafood stock and chicken broth slowly, stirring the entire time to keep the roux smooth. Add the bay leaves and fresh minced garlic once the liquid is fully incorporated.

Lower the heat until the pot holds a gentle simmer, then cover with a lid. The surface should show slow, lazy bubbles rather than a hard boil.

Let the gumbo simmer this way for 90 minutes, stirring occasionally. The liquid will thicken slightly and turn a deeper, richer brown as the flavors concentrate.

While the pot simmers, cook the rice and prepare any side dishes. This keeps everything ready to serve the moment the gumbo finishes.

Add the crab, shrimp, lump crab meat, green onions, and parsley, and bring the pot back to a boil. Cook on a slow, steady boil for 15 minutes, then turn off the heat as soon as the shrimp turn opaque and pink.