In a ziptop bag, combine the shrimp with the bloody Mary mix, 1 teaspoon of the celery salt and half of the lime juice. Cover and refrigerate for 3 to 4 hours.
Cook the frozen rice according to the package instructions. Cool to room temperature.
Drain the shrimp and reserve 2 tablespoons of the liquid. Transfer the shrimp and the reserved liquid to a medium bowl. Add the cilantro, red onion, avocado, remaining 1/2 teaspoon celery salt, remaining lime juice, a few dashes of hot sauce if desired and salt and pepper to taste. Serve in bowls over the rice with plantain chips.