Place the sausages onto a wired rack on top of a sheet pan and prick each sausage a couple times.
On a second sheet pan add the diced potatoes and onions and drizzle on olive oil and salt and pepper. Mix to combine and spread everything out in a single layer on the sheet pan.
Bake everything for 15 minutes before flipping the sausages and stirring the potatoes before baking for another 15 minutes.
Remove the sausages and increase the heat to 450F and bake for another 20-30 minutes, keeping an eye on it and removing the red onions if they start to burn.
When done, let everything cool and portion out into your meal prep containers.