Shrimp Remoulade

1 1/2 tablespoons dry mustard 
2 tablespoons vegetable oil 
1 tablespoon vinegar 
1 tablespoon prepared horseradish 
1 teaspoon paprika 
1/2 teaspoon salt 
1/4 teaspoon white pepper 
dash of cajun hot sauce (tobasco will do in a pinch) 
2 green onions, sliced in 1-inch pieces 
1/2 Stalk celery, sliced in 1/2-inch pieces 
2 tablespoons coarsely chopped fresh parsley 
1 clove garlic, halved 
2 Pounds medium shrimp, cooked and deveined 
lettuce leaves or mixed salad greens 

Combine all ingredients except shrimp and lettuce in container of an electric blender or food processor; process until well-blended and smooth. Chill shrimp remoulade thoroughly. To serve, arrange shrimp on lettuce leaves; pour dressing over shrimp.