Preheat the oven to 425 degrees F (220 degrees C). Line a baking sheet with parchment paper.

Place potatoes, onion, and bell pepper into a large bowl. Add olive oil, garlic powder, salt, and pepper; mix well. Transfer to the prepared baking sheet.

Roast in the preheated oven, stirring halfway through, until potatoes are tender, about 30 minutes.

Turn on the broiler and broil until crispy, checking often to prevent burning, 2 to 5 minutes.