Chop the shrimp into small pieces and place in a bowl.
Pour lime juice over the shrimp and cover the bowl. Refrigerate for 15-20 minutes.
Prepare the vegetables: dice the tomato, cucumber, and jalapeño, and chop the red onion and cilantro.
Once the shrimp is opaque, drain excess lime juice if desired.
Add the diced vegetables to the shrimp and mix gently.
Season the mixture with salt and pepper to taste.
Serve chilled, garnished with avocado slices and lime wedges.