Prep all ingredients: chop the onion, mince the garlic, cut sausage into rounds (or remove from casings), cut broccoli into small florets, and chop the red bell pepper.
Heat 1 tablespoon olive oil in a large soup pot over medium-high heat.
Add the chicken sausage and sauté for about 5 minutes, until browned.
Add the chopped onion and cook for about 4 minutes, until softened.
Stir in the minced garlic and the uncooked orzo and cook for 30 seconds, stirring constantly.
Add 1/4 teaspoon Italian seasoning, 2 cups chicken broth, and 14 fluid ounces tomato sauce; stir to combine and bring to a gentle simmer.
Once simmering, add the broccoli florets and chopped red bell pepper. Reduce heat to medium or medium-low so the mixture gently bubbles, not vigorously boils.
Continue cooking uncovered for about 10 minutes, stirring often to prevent the orzo from sticking, until the orzo is tender and liquid is mostly absorbed.
Season with salt and pepper to taste and serve immediately with freshly grated Parmesan if desired.