Preheat the oven: Set to 425°F (220°C). High heat means caramelized edges and fast cooking.
Prep the pan: Line a large rimmed sheet pan with parchment for easy cleanup, or lightly spray with cooking spray.
Slice the sausage: Cut into 1/2-inch rounds. If using raw sausage, slice carefully or cut into chunks.
Precooked works great too.
Chop the veggies: Keep pieces similar in size for even roasting. Halve any big tomatoes so they burst and sweeten.
Season: In a large bowl, combine sausage and veggies. Add olive oil, garlic, smoked paprika, Italian seasoning, salt, pepper, and red pepper flakes.
Toss until evenly coated.
Spread out: Arrange everything in a single layer on the sheet pan. Avoid crowding so the veggies roast instead of steam.
Roast: Bake for 20–25 minutes, stirring once halfway through. You’re looking for browned edges and tender veggies.
Add brightness: Zest half the lemon over the hot tray, then squeeze on 1–2 teaspoons of juice. Toss gently.
Finish and serve: Sprinkle with chopped parsley.
Taste and adjust salt and pepper. Serve as is, or over a bed of greens or cauliflower rice.