Preheat oven to 425°F. Spray a large sheet pan with non-stick cooking spray. Set aside.
In a bowl, whisk together olive oil, juice from 1 lime, chili powder, salt, pepper, garlic powder, cumin, and onion powder.
Place onions and peppers on a prepared sheet pan. Pour half of the marinade over the veggies. Transfer pan to oven and roast for 15 minutes.
Meanwhile, add shrimp to the bowl with the remaining half of the marinade and marinate shrimp while the veggies are roasting in the oven.
Once the veggies are finished cooking, push them to one side, add the shrimp and both halves from the remaining lime, flesh side down. Continue cooking for 5-6 minutes, until shrimp turns pink and opaque (making sure not to overcook shrimp or it will turn rubbery).
Serve immediately with warm tortillas, sour cream, avocado, and fresh cilantro. Enjoy!