How to Make It
Fill a bowl with ice water. In a medium saucepan of salted boiling water, cook the shrimp until just white throughout, about 3 minutes. Drain and transfer the shrimp to the ice bath to cool, then drain and halve lengthwise. Transfer the shrimp to a bowl, cover and refrigerate.
In a large bowl, mix the lemon juice, lime juice, jalapeño juice and 1 tablespoon of salt. Immerse the snapper in the juices, cover and refrigerate for at least 2 hours and up to 4 hours.
Drain the snapper and return it to the bowl. Add the onion, cilantro and shrimp and mix well. Season with salt. Transfer the ceviche to a serving platter and drizzle with the sesame oil. Garnish with the sesame seeds and avocado wedges and serve with tortilla chips.