Place the peeled shrimp in a bowl and add the lime juice for a marinade. Add just enough water to cover the shrimp completely, stir, and set aside for 20 minutes.
In a large bowl or directly on the rimmed baking sheet, toss the peppers and onion with 2 tablespoons of the olive oil. Spread the veggies out onto the baking sheet.
When the shrimp are finished in their marinade, drain and toss with the remaining tablespoon of olive oil.
Season the vegetables with about half of the garlic powder and half of the salt.
Bake the vegetables at 375°F for 35 minutes, or until wilted but not browning.
After 35 minutes, add the shrimp to the sheet pan by placing them directly on top of the vegetables. Season the shrimp with the remaining garlic powder and sea salt. Return the pan to the oven for an additional 10 to 15 minutes, or until the shrimp are cooked through.
To serve, garnish with the cracked black pepper, fresh cilantro, and lime wedges. Enjoy!