Sausage, Shrimp, and Okra Gumbo

I follow Poppy Tooker's famous recipe which also reminds me of my mom's method. For Christmas, I make Poppy's seafood gumbo with crabs, shrimp and oyster. The recipe below is for shrimp and okra but if you click the link above you'll have the seafood version. Both are great! However, now that I am gluten free I'll need to come up with an alternative for the roux.

Ingredients:

Smoked pork sausage
2 pounds shrimp
1 pound fresh okra
Pork fat (or lard, oil, etc) and 3/4 cup arrowroot starch and 1/4 cup white flour for roux
1/2 cup oil
1 cup flour
1 onion, chopped
1 bell pepper, chopped
3 stalks celery, chopped
1 1-pound can crushed tomatoes
1 gallon shrimp or chicken stock
1 clove garlic
2 teaspoons thyme
1 bay leaf
1 bunch green onions
Crystal Hot Sauce to taste

Method of Preparation:

Peel shrimp and combine peels, onion skins and tops in a stock pot. Cover with water and boil for 20 minutes.
Strain and reserve.
Fry okra in very hot oil until lightly browned (or roast).
Make a dark roux with the flour and oil, cooking to the color of milk chocolate brown. Add onions, stirring together until the roux darkens to a bittersweet chocolate brown. Add celery and bell pepper. Sauté for five minutes, then add the gumbo crabs, tomatoes, okra, herbs and shrimp stock. Add garlic and salt and pepper to taste. Simmer 45 minutes or longer.
Ten minutes before serving add shrimp and green onions. Add Crystal Hot Sauce and salt as needed. Serve on top of cooked rice.

My notes - So good a little oily reminded me of my Gran's gumbo - I think it was the sausage.