01 - Preheat the oven to 425°F. Line a large rimmed baking sheet with parchment paper or foil to ensure easy cleanup.
02 - Slice the red, yellow, and green bell peppers, along with the large red onion, into even strips. Arrange them evenly on the prepared baking sheet.
03 - Drizzle the olive oil over the sliced vegetables, then sprinkle with dried oregano, dried basil, garlic powder, smoked paprika, kosher salt, and black pepper. Toss gently to coat all vegetables evenly.
04 - Nestle the Italian sausages among the seasoned vegetables on the baking sheet to ensure even roasting.
05 - Place the baking sheet in the preheated oven and roast for 25 to 30 minutes. Halfway through, flip the sausages and stir the vegetables to promote even cooking. Confirm sausages reach an internal temperature of 160°F and vegetables are tender and caramelized.
06 - Remove from oven, garnish with chopped fresh parsley if desired, and serve hot. This dish pairs well on its own, in hoagie rolls, or over rice or pasta.