Add white rice and water to a pot with a pinch of salt. Bring to a boil, then reduce to low heat, cover, and cook for 12-15 minutes, or until the water is absorbed. Remove from heat, let sit covered for 5 minutes, then fluff with a fork.

Preheat the oven to 400°F (200°C) and line a sheet pan with parchment paper.

Add the bell peppers and onion to the sheet pan. Toss with about two-thirds of the oil and two-thirds of the taco seasoning, then spread into a single layer. Roast for 15-18 minutes, until softened.

Meanwhile, add the peeled shrimp to a mixing bowl and toss with the remaining oil and taco seasoning.

Remove the sheet pan from the oven and push the vegetables to one side. Add the shrimp to the other side in a single layer (use a second pan if needed).

Return to the oven and cook for 8-10 minutes, until the shrimp are opaque and fully cooked and the vegetables are soft.

Serve the rice topped with the pepper mixture and shrimp. Add guacamole on top and serve.