In a large bowl, combine the diced tomatoes, red onion, cucumber, and cilantro.
Add the cooked shrimp and diced avocado to the bowl.
In a separate bowl, mix the tomato juice, ketchup, hot sauce, and lime juice to make the cocktail sauce.
Pour the cocktail sauce over the shrimp and vegetable mixture, and gently toss to combine.
Season with salt and pepper to taste.
Cover the bowl with plastic wrap and refrigerate for at least 30 minutes to allow the flavours to meld.
Serve the Shrimp Campechana in individual glasses or bowls, and garnish with additional cilantro and lime wedges if desired.
Accompany with tortilla chips for scooping and enjoy!