Preheat the oven: Heat to 425°F (220°C). Line a large sheet pan with parchment for easier cleanup.
Par-cook the potatoes (optional but helpful): If using larger chunks, microwave them for 3–4 minutes until just starting to soften. This ensures everything finishes at the same time.
Prep the sausage and veggies: Slice the sausage into rounds.
Cut the peppers into strips, the onion into wedges, zucchini into half-moons, and tomatoes left whole.
Season: In a large bowl, combine sausage, potatoes, peppers, onion, zucchini, and tomatoes. Add olive oil, salt, pepper, garlic powder, Italian seasoning, smoked paprika, and red pepper flakes. Toss until everything is evenly coated.
Arrange on the pan: Spread the mixture in a single layer.
Avoid crowding; use two pans if needed for better browning.
Roast: Bake for 25–30 minutes, stirring once halfway through. You want caramelized edges on the veggies and browned sausage.
Finish and taste: Remove from the oven and drizzle with balsamic vinegar or a squeeze of lemon. Toss gently.
Taste and adjust seasoning with more salt and pepper if needed.
Serve: Garnish with chopped parsley or basil. Add a sprinkle of Parmesan if you like. Serve as is, or over rice, quinoa, or with crusty bread.