Chop onion, celery, and bell pepper and set aside.
Dice sausage into ½ inch cubes and set aside.
Mince garlic and set aside.
Heat ditch oven (or large pot) over medium high heat and add 1 teaspoon oil.
Add sausage and cook until browned, about 5 minutes, stirring occasionally.
Remove sausage from pot and set aside.
Add onion, celery, and bell pepper to pot plus 1 teaspoon oil.
Sauté for 10 minutes, stirring occasionally.
Add garlic and sauté for 1 minute.
Add tomato paste, Cajun seasoning, salt, pepper, and thyme. Mix well and sauté for 3 minutes.
Add chicken stock, water, Worcestershire sauce, hot sauce, sausage, beans, and bay leaf.
Cover with lid, reduce heat to low and simmer for 2 hours.
While stock is simmering, cook rice according to package instructions.
Remove bay leaf and discard.
To thicken the stock, in a small bowl add two tablespoons of stock from the pot plus 2 tablespoons cornstarch. Mix with a fork until well combined. Add the cornstarch slurry to the pot and mix well. Bring back to a boil, then reduce heat to simmer and let cook for 5 minutes.
Add rice to the pot and mix well.
Garnish with green onion and parsley.