In a large Dutch oven, heat butter. Place sausage in the pot and cook for 3 minutes. Scoop out into a bowl. Add chopped vegetables and seasonings to the pot along with diced tomato. Cook over medium heat for 2-3 minutes, stirring often.
Add sausage back into the pot. Stir in the brown rice and chicken broth. Increase heat to high and bring to a heavy simmer. Immediately reduce heat to low, cover Dutch oven with lid and let cook for 35-40 minutes.
Check rice for doneness. If it is tender then stir in the shrimp, cover, and cook for 5 minutes. If not, cook rice for another 5-10 minutes or until it becomes tender, then follow the steps above. Taste for salt content and adjust accordingly.
Once cooked, remove the pot from heat. Spoon out the desired amount and garnish with sliced green onion.
Store leftover jambalaya in an airtight container in the refrigerator for up to 3 days after preparation. Reheat well before serving.