Shrimp Etouffee

2 pounds shrimp (precooked with tails is fine. Just thaw under cold running water and remove tails.)
1/4 pound butter or 3 T. oil
1 cup chopped onion
1/2 cup celery, chopped fine
1/2 cup bell pepper, chopped fine
4 cloves garlic, pressed
3 Tablespoons cornstarch
1 1/2 cups water
Salt, pepper & cayenne pepper to taste

Season shrimp generously with salt, pepper and cayenne. (Well, go easy w/ cayenne unless you like it hot) Set aside.
Add onions, celery, bell pepper and garlic to oil or butter. Cook slowly until wilted. Add shrimp and let simmer on low heat for 20 minutes. Dissolve cornstarch in water and add to mixture. Cook 15 minutes longer. Stir occasionally. Add 1 heaping tablespoon of tomato paste. Serve over rice.