Preheat the oven to 450°F (230°C). Grease a baking sheet with cooking spray.
STEP 2
Mix olive oil and onion soup mix in a large bowl until combined. Add potatoes, carrots, bell peppers, and onion; mix until well coated. Spread evenly onto the prepared baking sheet.
STEP 3
Roast in the preheated oven until vegetables are tender, about 15 to 30 minutes.