If you’re choosing uncooked shrimp, start by peel, devein and rinse the shrimp. Chop into 1/2 inch pieces and transfer to a bowl. If you’d prefer cooked shrimp, prepare the same way and set aside.
In a small bowl, whisk together the lemon and lime juices. Pour over the shrimp and toss to combine. Allow the shrimp to marinate in the juice for 15 minutes.
Add the tomato, cilantro, chili pepper, and red onion to the shrimp. Toss the ingredients to combine and allow to marinate for an additional 10 minutes.
Stir in the chopped avocado, season with salt and pepper, to taste. Serve immediately over a bed of lettuce or with a side of tortilla chips, as desired.