Galatoire's Shrimp Remoulade

4 stalks celery, coarsely chopped
4 green onions, chopped
1 small onion, chopped
3/4 cup Italian flat leaf parsley
1/2 cup red wine vinegar
1/2 cup ketchup
1/2 cup tomato puree
1/2 cup Creole mustard
1 teaspoon Worcestershire sauce
1 1/8 cups vegetable oil
2 teaspoons paprika
2 pounds large cooked shrimp, peeled and deveined
12 lettuce leaves

In the container of a food processor, combine the celery, green onions, onion and parsley.
Pulse until finely chopped. Add the vinegar, ketchup, tomato puree, mustard and Worcestershire sauce.
Process until well blended, stopping to scrape down the sides a couple of times.
With the food processor running, drizzle the oil in a steady stream, processing until blended.
Stir in paprika.
Transfer to a bowl, cover and refrigerate for 6 to 8 hours, or overnight.
When ready to serve, stir the sauce, then pour over the shrimp and toss to coat.
Serve on top of lettuce leaves.