1 cup clam juice
¼ teaspoon dried oregano
1 pound large shrimp, peeled and deveined
1 ¼ cups peeled, seeded, diced ripe tomatoes
1 cup diced English cucumber
½ cup diced celery
½ cup finely diced red onion
2 tablespoons seeded and diced jalapeno peppers
½ cup ketchup
2 medium limes, juiced
2 tablespoons freshly chopped cilantro, plus more for garnish
1 dash Mexican-style hot sauce
1 large Hass avocado, cubed
Bring clam juice and oregano to a boil in a saucepan over medium-high heat. Add shrimp; cook and stir just until shrimp turn pink, about 2 minutes. (They will not be cooked through.) Transfer shrimp to a bowl with a slotted spoon; let cool to room temperature. Reserve liquid.
While the shrimp are cooling, combine tomatoes, cucumbers, celery, onion, and jalapeños in a mixing bowl. Gently mix in reserved cooking liquid, ketchup, lime juice, 2 tablespoons cilantro, and hot sauce until well combined.
Place four whole shrimp in a small bowl; cover with plastic wrap. Chop remaining shrimp into bite-sized pieces; add to vegetable mixture and stir to combine. Cover with plastic wrap. Refrigerate both bowls until thoroughly chilled, 2 to 3 hours.
When ready to serve, stir avocado into the shrimp cocktail. Divide into four glass bowls; top each with a chilled whole shrimp and garnish with cilantro.