Heat oil in a large, non-stick skillet over medium-high heat.
When the oil is shimmering, swirl the pan so the the oil evenly coats the skillet. Add shrimp in a single layer with salt and pepper. Cook shrimp until cooked through, about 2-3 minutes per side. Transfer cooked shrimp to a plate and set aside.
Reduce heat to medium and add ghee to skillet to melt. Add arrowroot and stir until combined with ghee, pressing all the clumps out with the edge of a spoon until smooth.
Add onions, celery, green onion, and bell pepper to the skillet. Season with cayenne, oregano, thyme, rosemary, crushed red pepper, bay leaf and paprika. Cook, stirring, until the vegetables are tender, about 4 minutes. (The roux, vegetables, and spices will become sticky and adhere to the bottom of the pan. Continue to cook for 4 minutes, or until the veggies have softened, stirring frequently. Brown bits will develop on the bottom of the pan but they will help increase the flavor.)
Add the *drained* diced tomatoes and fish sauce. While stirring, slowly pour in the chicken stock, until incorporated. Bring to a rapid simmer. Stirring often and scraping up and browned bits, allow sauce to reduce, about 5-7 minutes.
Once the sauce has thickened, reduce heat to low and return shrimp to the skillet. Stir to combine.
Taste shrimp and adjust seasonings, if desired.
Serve over prepared cauliflower rice and garnish with parsley and hot sauce.