Preheat the oven to 400°F (200°C).

Line a baking sheet with parchment paper.

Slice the bell peppers and onion into strips.

In a large mixing bowl, combine the sliced vegetables, minced garlic, olive oil, Italian seasoning, salt, and pepper. Toss until the veggies are well-coated.

Place the sausages on the prepared baking sheet and surround them with the seasoned vegetables.

Roast in the oven for about 25-30 minutes, until sausages are cooked through and vegetables are tender.

Ensure sausages reach an internal temperature of 160°F (70°C).

Remove from the oven, let cool for a few minutes, and serve.