01 -  Set oven to 425°F and allow to fully preheat. 
 02 -  In a large bowl, combine shrimp, sliced bell peppers, sliced onion, olive oil, fajita seasoning, salt, and pepper. Toss to coat ingredients evenly. 
 03 -  Spread the seasoned shrimp and vegetables in a single layer across a baking sheet. 
 04 -  Roast in the oven for 10 to 12 minutes or until shrimp turn pink and vegetables are tender. 
 05 -  Serve immediately with warm tortillas.