Heat the oil in a large pan over high heat. Add the peppers and onion to the pan and cook, stirring occasionally, until vegetables are tender and charred on the edges. Season the vegetables with salt and pepper.
In a small bowl, mix together the chili powder, cumin, garlic powder, onion powder, smoked paprika, and salt and pepper to taste.
Add the shrimp to the pan and sprinkle the seasoning blend over the shrimp and vegetables. Stir to combine.
Cook for 4-5 minutes or until shrimp are pink and opaque.
Sprinkle the cilantro over the top and serve. Garnish with lime wedges if desired. Serve the flour tortillas and toppings on the side and have everyone assemble their own fajitas.