Preheat your oven and a baking sheet to 425 degrees F.
Peel the onion and chop it into 1-inch pieces. Deseed the bell pepper and cut it into 1-inch pieces. Chop the potatoes into 1-inch cubes. Add the veggies to a large mixing bowl.
Add the olive oil, garlic powder, onion powder, salt, and pepper to the bowl and toss to coat. Carefully spread everything out in a single layer over the hot baking sheet
Roast for 20 minutes and then flip with a spatula. Cook for another 20 to 30 minutes or until the potatoes are fork-tender.
Transfer the veggies to a serving bowl and sprinkle with chopped parsley for garnish. Serve warm.
Notes
You can leave the skins on the potatoes or peel them. Both ways work just fine for this recipe and it is up to your preference.
This is a large batch of potatoes. Smaller batches will not need to cook as long, so keep an eye on them.