In a large skillet, combine oil, flour and file powder to form a roux. Cook over medium heat, stirring often until roux is very dark (be careful not to burn).
Add vegetables, garlic, spices and shrimp and continue to cook for five to seven minutes, stirring constantly to prevent burning. Meanwhile, bring shrimp stock and tomatoes to a boil. Slowly add roux mixture to boiling stock and mix well. Lower heat to a slow simmer, and cook 10 more minutes. Add hot sauce and cayenne pepper. Yield: 1 gallon