Heat oil in large, non-stick skillet over medium-high heat.

Add shrimp in single layer with salt and pepper. Cook shrimp until cooked through, about 2 to 3 minutes per side. Transfer cooked shrimp to plate and set aside.

Reduce heat to medium and add ghee to skillet to melt. Add flour and stir until combined with ghee, pressing all clumps out with the edge of spoon until smooth.

Add onions, celery, green onion and bell pepper to skillet. Season with cayenne, oregano, thyme, crushed red pepper, bay leaf and paprika. Cook until vegetables are tender, about 4 minutes.

Add diced tomatoes and fish sauce. While stirring, slowly pour in chicken stock until fully incorporated and bring to rapid simmer. Stirring often, allow sauce to reduce for about 5 to 7 minutes.

Once sauce has thickened, reduce heat to low and return shrimp to skillet. Stir to combine and serve over rice.