Bring a large pot of water to a boil. Once water is boiling, place shrimp into boiling water and allow to boil for 3-5 minutes until just cooked through. Rinse with cold water to stop the cooking process. Peel shrimp and chop into bite sized pieces.
Add chopped shrimp into a large mixing bowl. Add in diced tomatoes, onion, pickeld serrano chiles, serrano chile, and cilantro and mix together. Add lemon juice, lime juice, and salt.
Wear plastic cooking gloves. Using your hands, squeeze the ceviche mixture and mix around approximately 1 minute. This allows the flavors of the ingredients to combine.
Place ceviche in the refrigerator overnight.
The next day, taste for seasoning and add salt or lemon juice as needed. Serve with fresh avocado and tortilla chips or tostadas.