Heat a large heavy-bottomed saucepan and cook the salt pork over medium-high heat until crisp. Add the red and green peppers, celery, onion, and garlic and cook 3 to 4 minutes. Add the rice and stir, coating the rice with drippings. Stir in the tomatoes, tomato paste, water, salt, and black and cayenne pepper. Cover and simmer until the rice is tender and the liquid is absorbed, about 25 to 30 minutes.