Brown the sausage in olive oil over medium-high heat for 4-5 minutes until golden on both sides. Those caramelized bits create flavor that permeates the entire dish. Remove sausage and set aside on a plate.
Sauté the aromatics in the same pot using those beautiful browned bits. Cook diced onion for 3 minutes until softened, then add garlic for 30 seconds until fragrant. Your kitchen should smell amazing right now.
Toast the orzo for 2 minutes, stirring constantly so each grain gets coated in that flavorful oil. Toasting adds nutty depth you won't get if you skip this step.
Pour in liquids and bring to a boil, then reduce to medium-low heat. Add browned sausage back to the pot along with sun-dried tomatoes and Italian seasoning. Stir everything together so flavors distribute evenly.
Simmer covered for 12-15 minutes, stirring every 4 minutes to prevent sticking. The orzo will absorb liquid and become tender while soaking up all those savory flavors. Add more water if it looks dry.
Add broccoli and tomatoes in the last 5 minutes of cooking so vegetables stay crisp-tender. Stir gently to incorporate without breaking up the tender orzo. Season with salt and pepper to taste.
Finish with Parmesan and lemon off the heat, stirring until cheese melts into a creamy coating. The lemon juice adds brightness that balances the richness perfectly. Garnish with fresh basil before serving.