Preheat Blackstone griddle to medium heat. Drizzle vegetable oil then add celery, onion, bell pepper, and the white green onions. Cook for 5-7 minutes until tender.
Add the chicken, sausage, and diced tomatoes. Cook for another 3-4 minutes. Season to taste with Cajun seasoning.
Add the tortellini to the griddle. Stir with spatulas until evenly mixed with the meat and vegetables. Pour a cup of water over the tortellini to create steam. Stir for another minute.
Pour the Italian dressing over the tortellini, stir until evenly mixed. Season with more Cajun seasoning if necessary. Remove from the griddle and top with the remaining green onions. Serve immediately.
