Cook the Shrimp - In a medium saucepan bring water and 1 ½ teaspoon of salt to a boil. Turn off the heat and add the shrimp. Allow it to cook until opaque, about 2 to 3 minutes. Immediately transfer to a colander and rinse with cold water until cool, about 1 to 2 minutes.
Chop Into Pieces - Chop the cooked shrimp into ½-inch pieces—place in a large non-reactive bowl.
Prepare Mix-ins - To the bowl of shrimp, add tomatoes, cucumber, onion, cilantro, serrano pepper, lime zest, lime juice, lemon juice, and ½ teaspoon salt. Stir to combine. Cover and refrigerate for 30 minutes, stirring halfway through.
Add Avocado - Right before serving stir in the diced avocado. Taste and season with more salt as desired.
To Serve - Pair shrimp ceviche with chips or on tostadas.
Notes
Recipe Yield: 5 cups
Serving Size: 1/2 cup
Storing: Place in an airtight container for up to 2 days before serving.