Make the sauce:
In a food processor, combine the vinegar, mustards, tomato paste, garlic, Tabasco, lemon juice, egg, and paprika. Pulse to mix. With the processor running, slowly add the oil in a steady stream. Add the scallions, celery, parsley, and salt to taste; pulse briefly to combine. Overprocessing may cause separation. Chill.
Prepare the shrimp:
In a 6- to 8-qt. pan, combine 1 gallon water with 1/4 cup of the salt, the cayenne, peppercorns, lemon, garlic, bay leaves, and onion. Bring to a boil and then simmer for 15 minutes. Add the shrimp and cook until they’re pink and just barely opaque through the center, about 3 minutes. Pull the shrimp from the boil and put them in a large bowl. Cover with ice and then add 2 cups of the boil liquid to the iced shrimp. Soak for 5 minutes. Add the remaining salt. When the shrimp are well chilled, drain.
Before serving, dip each shrimp in the rémoulade sauce to coat and arrange on a bed of the lettuce.
Make Ahead Tips
The rémoulade sauce may be made a day in advance, but it's best to cook the shrimp an hour or so before serving.
nutrition information (per serving):
includes sauce, Calories
15, Fat Calories
140, Saturated Fat
14, Monounsaturated Fat
2, Polyunsaturated Fat