1. Brown Italian sausage in a Dutch oven over medium-high heat, stirring often, 5 minutes or until sausage crumbles and is no longer pink. Remove sausage from Dutch oven using a slotted spoon, reserving drippings in Dutch oven.
2. Cook chicken and pork in hot drippings in Dutch oven over medium-high heat, stirring often, 4 to 5 minutes or until browned on all sides. Add frozen onion mixture and next 4 ingredients, and sauté 5 minutes. Stir in diced tomatoes and green chiles, tomato paste, 1/4 cup water, and Italian sausage; cover, reduce heat to low, and cook, stirring often, 20 minutes.
3. Stir hot cooked orzo into jambalaya just before serving, or serve over hot cooked pasta. Garnish, if desired.