Peel shrimp and reserves shells.
Toss peeled shrimp with one teaspoon of Cajun seasoning and place in refrigerator.
Place shrimp shells in a small saucepan and cover with one quart of water and stir in kosher salt.Cover and simmer for 20 minutes.
Heat bacon grease in a large skillet. Add onion, celery and bell pepper and cook on medium heat until vegetables are soft and volume has reduced by half, stirring as needed.
Strain shrimp shells from liquid and add liquid to softened vegetables.
Stir in tomatoes, tomato paste, Worcestershire sauce and chili powder. Simmer, uncovered, for 30 minutes or until most of the liquid evaporates.
Add seasoned shrimp and cook for 2 to 3 minutes until the shrimp turns pink.
Taste for seasoning before serving and adjust as needed.
Serve over rice. Garnish with celery leaves.