In a large saucepan, combine 6 cups water, smashed lemongrass pieces, bay leaves, peppercorns, kosher salt, and sugar. Bring to a gentle boil over medium-high heat, stirring briefly to dissolve the salt and sugar.

Poach shrimp

Once the liquid reaches a gentle rolling boil, reduce heat so it simmers. Add the shrimp in a single layer and return to a simmer. Cook until shrimp are opaque and just cooked through, about 2 to 3 minutes for jumbo shrimp (depending on size). Do not overcook.

Shock shrimp

Immediately transfer the cooked shrimp with a slotted spoon to a bowl of ice water to stop cooking and firm the texture. Let chill for at least 3 minutes until completely cold.

Peel & chill

If not already peeled/deveined, peel and devein while tails remain on for presentation. Pat dry and refrigerate on a bed of crushed ice until ready to serve.

Sriracha Cocktail Sauce

In a medium bowl, whisk together ketchup, prepared horseradish, 2 tablespoons lemon juice, sriracha, Worcestershire sauce, optional hot sauce, salt, and black pepper until smooth and well combined. Taste and adjust heat (add more sriracha) or acidity (more lemon) as desired. Chill in refrigerator for at least 15 minutes to let flavors meld.

Lemongrass-Remoulade (creamy dipping)

Combine mayonnaise, Dijon mustard, 1 tablespoon lemon juice, finely minced lemongrass, chopped capers, minced shallot, paprika, optional hot sauce, salt, and black pepper in a small bowl. Stir until smooth. Refrigerate at least 10 minutes to let the lemongrass mellow and flavors marry. Adjust seasoning to taste.

Garnish & Serve

Fill individual serving glasses or a shallow platter with crushed ice. Arrange chilled shrimp over the ice with tails draped over the rim of glasses or placed decoratively on the platter.

Place small bowls of Sriracha Cocktail Sauce and Lemongrass-Remoulade alongside or in the center. Garnish sauces with a sprinkle of chopped chives or parsley and a lemon wedge on each serving. Serve immediately.