Heat vegetable oil in a large pot or Dutch oven over medium-high heat.

Make a roux by whisking in flour, a little at a time, into the hot oil. Stir constantly to prevent burning.

Cook the roux until it turns a dark brown color, which may take 10-15 minutes, stirring constantly.

Add celery, onion, and bell pepper to the pot and cook until they begin to soften, about 5 minutes.

Add garlic and andouille sausage and cook for another 5 minutes, stirring occasionally.

Slowly pour in white wine, clam juice, tomato sauce, and chicken stock, stirring to combine.

Season with salt, white pepper, thyme, oregano, cayenne, and bay leaf.

Bring the gumbo to a simmer, then reduce heat to medium-low and cook for 20-30 minutes, or until thickened.

Add the shrimp and cook until they turn pink and are cooked through, about 5-7 minutes.

Taste and adjust seasonings as needed.

Remove the bay leaf before serving.

Serve the gumbo hot over cooked rice.

Garnish with chopped green scallions.