One IMPORTANT note, this recipe made about twice as much roux as I needed, so consider that when making this. I guess some recipes scale better than others. I would be interested in other people's experience and opinions on this.

I made the roux the day before I needed it, which saved me time on event day. When ready to cook, I added all vegetables, stock, seasoning, tomatoes, etc. to a pot, heated them to a simmer, THEN added roux until I had the consistency I wanted. I would have had a mess if I added all the roux at once.

Recipe:

Make the roux: Heat oil. Whisk flour (a little at a time) into oil to form a paste. Continue cooking over low heat and whisk continuously, until the mixture turns a caramel color and gives off a nutty aroma, about 15 to 20 minutes.

To the roux, add the onion, green pepper, celery, and garlic and cook over low heat about 5 minutes, until the vegetables are limp.

Add the black pepper, white pepper, cayenne pepper, Cajun seasoning, green onions, parsley, and hot sauce to taste.

Add can clam juice and the tomatoes with their juice, stir to blend.

Add the salt, starting with 1 tablespoon, then add more if needed. Bring the mixture to a boil, reduce the heat to low and simmer for 30 minutes.

Remove from heat. Add the butter and stir; the heat from the dish will melt the butter.

Canola Oil - 6 cups
Flour - 6 cups
Onion -12 cups
Bell pepper - 6 cups
Celery - 12 cups
Minced garlic - 1/2 to 3/4 cups
Black pepper - 2 tablespoons
White pepper - 2 tablespoons
Cayenne - to taste
Cajun seasoning - 2.5 tablespoons, more if needed
Green onions - 6 cups (6 to 8 bunches)
Clam juice - 3 to 4 quarts (start with 3, more as needed)
Diced Tomatoes - one #10 can, plus four 14.5 cans) Sub in some Rotel for flavor
salt - 2.5 tablespoons
butter - 4 sticks of butter (start with 3, add more as needed)