Prep. Preheat the oven to 400ºF. Line a large baking sheet with aluminum foil for easy cleanup.
Wash and cut the veggies. Wash the yellow and green bell peppers. Cut them in half, remove the seeds and membranes, and slice the pepper halves into thick slices. Peel the onion and cut it into wedges.
Add seasonings. In a bowl, toss the bell pepper wedges and onion wedges with ½ tablespoon of olive oil. Season the mixture with salt and pepper to taste.
Bake the sausages. Add the sausages and prepared veggies to the lined baking sheet. Drizzle the remaining olive oil over the sausages. Bake the sausages for 25 minutes, flipping them halfway through. This step ensures that the bottom and top of the sausages get caramelized during the cooking process.
Enjoy! Serve the Italian sausages warm with veggies on the side.
Notes
If you're unsure whether the sausages are fully cooked, use a meat thermometer. They should have an internal temperature of 160°F
The sausages come with the casing, which you should not remove. Also, do not rip or pierce the casing because all the juices will leak.
If you are using frozen sausages, there's no need to thaw them. Increase the baking time by 10-15 minutes to ensure they are cooked.
You can use other types of sausages, like beef or turkey.
You can bake the sausages without veggies on the side and serve them with your favorite condiment.