Heat the oven to 425 °F. On a large rimmed sheet pan, toss the bell peppers and onion with 1 tbsp of the olive oil, 1 tsp chili powder, 1 tsp cumin and 1/4 tsp salt. Spread in a single layer and roast for 12 minutes.
While the vegetables roast, pat the shrimp dry and toss with the remaining 1 tbsp olive oil, 1 tsp chili powder, 1 tsp cumin, the garlic powder, 1/2 tsp salt and the lime zest.
Pull the pan from the oven and push the vegetables to the edges. Add the shrimp to the center in a single layer. Roast 6 to 8 minutes, until the shrimp are pink and opaque and the peppers are tender.
Squeeze the lime juice over the pan and stir everything together. Warm the tortillas.
Spoon the shrimp and peppers into the tortillas and top with cilantro.