Bring a medium pot of salted water to a boil. Meanwhile, prepare an ice bath in a large mixing bowl.
Once boiling, remove water from heat and carefully add the shrimp. Stir gently and allow shrimp to poach until pink and just cooked through, about 3 to 5 minutes depending on the size of your shrimp. Transfer cooked the shrimp to an ice bath and let stand until completely cool, about 10 minutes. Drain the shrimp and cut into bite-size pieces.
In a large mixing bowl, combine the cooked shrimp, lime juice, lemon juice, Roma tomatoes, cilantro, jalapeño, red onion, and kosher salt and toss to combine. Taste and adjust seasoning with more salt and citrus as needed.
Store ceviche in the fridge for at least 30 minutes and add cubed avocado just before serving. Serve on a bed of mixed greens or with tortilla chips if desired.
*not including bed of greens or tortilla chips