Peel and wash shrimp thoroughly.

In a deep skillet, heat shortening over medium heat.

Add flour to the hot shortening, creating a roux.

Cook the roux on medium heat, stirring constantly until it becomes dark brown.

Add chopped onion, green onions, green pepper, and celery to the roux.

Cook until vegetables are softened.

Add Ro-Tel tomatoes and tomato sauce to the skillet.

Season with salt, pepper, and Worcestershire sauce.

Simmer the sauce, covered, for 30 minutes to allow flavors to meld.

Bring the sauce to a boil.

Add the peeled and washed shrimp to the boiling sauce.

Cook for approximately 20 minutes, or until the shrimp are pink and cooked through.

Serve hot over rice.