Using fresh or frozen, boil the shrimp until they are fully cooked. Let them cool.
Peel the shrimp if not already peeled, and chop the shrimp into very small pieces.
In a large bowl, add shrimp and the juice of 4-5 limes depending on how juicy they are. Refrigerate for at least 1 hour. The longer the better!
Once the shrimp has marinated in the lime juice for at least 1 hour, season with salt.
Chop the tomatoes, cilantro, and mince the onion and add them to the shrimp.
Chop up pickled jalapenos and add them to shrimp along with a splash of the juice from the jar/can. You can also use a fresh jalapeno to your liking of spiciness.
Once you mix shrimp and veggies, add more of any ingredient it might be lacking. Add more salt if needed.
Serve with tostadas or chips. Refrigerate if not eating immediately.