Preheat oven to 400 degrees F (200 degrees C). Line a baking sheet with parchment paper.
In a large bowl, combine sweet potatoes, bell peppers, red onion and garlic. Drizzle with olive oil and sprinkle with sea salt and pepper. Toss to coat.
Spread vegetables on the prepared baking sheet in a single layer. Roast for 30 minutes or until vegetables are tender.