2 tbs. kosher salt
2 lbs. small to medium white shrimp, peeled and deveined
1 cup fresh lime juice
1 cup clam juice
5 Roma (plum) tomatoes, cored and quartered
3 garlic cloves
1 bunch cilantro, coarsely chopped
3 Mexican oregano sprigs, coarsely chopped
1 tsp. celery seeds, toasted
1 red onion, diced
1 cup diced celery
2 jalapenos, thinly sliced
4 avocados, diced
1 (4-ounce) bag uncooked prawn crackers or bagged shrimp chips
Neutral oil, such as canola or grapeseed, for frying
In a medium stockpot, bring 4 quarts water to rolling boil. Fill large bowl with ice and water and set it nearby. Add salt to the boiling water, then add shrimp and cook until pink and opaque, about 1 minute. Immediately transfer to the ice bath to cool. Drain, transfer to a large nonreactive bowl, and add the lime juice. Cover and refrigerate for 1 to 2 hours.
In a blender, combine clam juice, tomatoes, garlic, cilantro, oregano, and celery seeds and pulse just a few times so the mixture remains chunky. Add onion to shrimp, stir, and let mellow for 2 to 3 minutes. Pour tomato mixture over shrimp. Add celery, jalapenos, and avocados. Stir gently so as not to smash the avocados. Refrigerate until chilled, up to 4 hours.
If using prawn crackers, fill a Dutch oven or heavy-bottomed stockpot with 2 inches of oil and clip a deep-fry thermometer to the side. Heat over medium-high heat to 350°F. Set a wire rack over a baking sheet. Drop 3 or 4 crackers into the hot oil, leaving room for them to expand, and cook until they puff up, about 15 seconds. Using a slotted spoon, transfer the crackers to the rack. Repeat with the remaining crackers, letting the oil return to 350°F between batches. Transfer the shrimp to a serving bowl and serve chilled.