Place the shrimp in a large mixing bowl. Add 1/2 cup lime juice and let stand for 15 minutes so the shrimp can "cook" in the lime juice (any less and it won't cook, any more and it toughens).
Meanwhile, in a separate large mixing bowl, mix the remaining 1/2 cup lime juice, cucumbers, tomatoes, cilantro, red onions and serrano chile to incorporate evenly.
Transfer the mixed vegetables into the shrimp bowl and mix well to incorporate.
Season the ceviche with some salt.
Serve in lettuce wraps, top with avocado and hot sauce.